diff --git "a/1b4-R6NjZOA.txt" "b/1b4-R6NjZOA.txt" new file mode 100644--- /dev/null +++ "b/1b4-R6NjZOA.txt" @@ -0,0 +1,10231 @@ +align:start position:0% + +[Music] + + align:start position:0% + + + + align:start position:0% + +oh + + align:start position:0% +oh + + + align:start position:0% +oh +[Music] + + align:start position:0% +[Music] + + + align:start position:0% +[Music] +[Applause] + + align:start position:0% +[Applause] + + + align:start position:0% +[Applause] +[Music] + + align:start position:0% + + + + align:start position:0% + +hi in the last + + align:start position:0% +hi in the last + + + align:start position:0% +hi in the last +session we looked at the possibility of + + align:start position:0% +session we looked at the possibility of + + + align:start position:0% +session we looked at the possibility of +comp compensating a feedback system by + + align:start position:0% +comp compensating a feedback system by + + + align:start position:0% +comp compensating a feedback system by +using minor Loop compensation where we + + align:start position:0% +using minor Loop compensation where we + + + align:start position:0% +using minor Loop compensation where we +construct a system that has two Loops by + + align:start position:0% +construct a system that has two Loops by + + + align:start position:0% +construct a system that has two Loops by +adjusting the feedback element or + + align:start position:0% +adjusting the feedback element or + + + align:start position:0% +adjusting the feedback element or +properly select collecting the feedback + + align:start position:0% +properly select collecting the feedback + + + align:start position:0% +properly select collecting the feedback +element in an inner or minor loop we're + + align:start position:0% +element in an inner or minor loop we're + + + align:start position:0% +element in an inner or minor loop we're +able to compensate the + + align:start position:0% +able to compensate the + + + align:start position:0% +able to compensate the +system in today's session and the + + align:start position:0% +system in today's session and the + + + align:start position:0% +system in today's session and the +following one I'd like to look at how we + + align:start position:0% +following one I'd like to look at how we + + + align:start position:0% +following one I'd like to look at how we +do this with an actual existing + + align:start position:0% +do this with an actual existing + + + align:start position:0% +do this with an actual existing +operational amplifier and how we choose + + align:start position:0% +operational amplifier and how we choose + + + align:start position:0% +operational amplifier and how we choose +compensation in particular minor Loop + + align:start position:0% +compensation in particular minor Loop + + + align:start position:0% +compensation in particular minor Loop +compensation to tailor that operational + + align:start position:0% +compensation to tailor that operational + + + align:start position:0% +compensation to tailor that operational +amplifier to a variety of + + align:start position:0% +amplifier to a variety of + + + align:start position:0% +amplifier to a variety of +applications the amplifier that we're + + align:start position:0% +applications the amplifier that we're + + + align:start position:0% +applications the amplifier that we're +going to use is one that's been in + + align:start position:0% +going to use is one that's been in + + + align:start position:0% +going to use is one that's been in +existence for 10 or 15 years + + align:start position:0% +existence for 10 or 15 years + + + align:start position:0% +existence for 10 or 15 years +it's the type 101a or equivalently the + + align:start position:0% +it's the type 101a or equivalently the + + + align:start position:0% +it's the type 101a or equivalently the +301a the difference between those two + + align:start position:0% +301a the difference between those two + + + align:start position:0% +301a the difference between those two +designations simply reflects the + + align:start position:0% +designations simply reflects the + + + align:start position:0% +designations simply reflects the +temperature range over which + + align:start position:0% +temperature range over which + + + align:start position:0% +temperature range over which +specifications are guaranteed and a + + align:start position:0% +specifications are guaranteed and a + + + align:start position:0% +specifications are guaranteed and a +minor grade out on certain parameters so + + align:start position:0% +minor grade out on certain parameters so + + + align:start position:0% +minor grade out on certain parameters so +we'll use this readily available and + + align:start position:0% +we'll use this readily available and + + + align:start position:0% +we'll use this readily available and +quite inexpensive operational + + align:start position:0% +quite inexpensive operational + + + align:start position:0% +quite inexpensive operational +amplifier and there are several + + align:start position:0% +amplifier and there are several + + + align:start position:0% +amplifier and there are several +considerations that we have to factor + + align:start position:0% +considerations that we have to factor + + + align:start position:0% +considerations that we have to factor +into our thinking that reflect the + + align:start position:0% +into our thinking that reflect the + + + align:start position:0% +into our thinking that reflect the +reality of that amplifier + + align:start position:0% +reality of that amplifier + + + align:start position:0% +reality of that amplifier +first of all the amplifier is + + align:start position:0% +first of all the amplifier is + + + align:start position:0% +first of all the amplifier is +constructed using a commonly used + + align:start position:0% +constructed using a commonly used + + + align:start position:0% +constructed using a commonly used +integrated circuit process one of the + + align:start position:0% +integrated circuit process one of the + + + align:start position:0% +integrated circuit process one of the +limitations of that process has to do + + align:start position:0% +limitations of that process has to do + + + align:start position:0% +limitations of that process has to do +with fabrication of PNP transistors and + + align:start position:0% +with fabrication of PNP transistors and + + + align:start position:0% +with fabrication of PNP transistors and +a consequence of of that limitation is + + align:start position:0% +a consequence of of that limitation is + + + align:start position:0% +a consequence of of that limitation is +that if we form a feedback loop using + + align:start position:0% +that if we form a feedback loop using + + + align:start position:0% +that if we form a feedback loop using +the 101a type operational amplifier it's + + align:start position:0% +the 101a type operational amplifier it's + + + align:start position:0% +the 101a type operational amplifier it's +impossible to get crossover frequencies + + align:start position:0% +impossible to get crossover frequencies + + + align:start position:0% +impossible to get crossover frequencies +in the overall feedback loop much above + + align:start position:0% +in the overall feedback loop much above + + + align:start position:0% +in the overall feedback loop much above +a megahertz without the overall Loop + + align:start position:0% +a megahertz without the overall Loop + + + align:start position:0% +a megahertz without the overall Loop +becoming unstable and the reason for + + align:start position:0% +becoming unstable and the reason for + + + align:start position:0% +becoming unstable and the reason for +that as I say has to do with poor + + align:start position:0% +that as I say has to do with poor + + + align:start position:0% +that as I say has to do with poor +Dynamic performance associated with the + + align:start position:0% +Dynamic performance associated with the + + + align:start position:0% +Dynamic performance associated with the +lateral pnps in particular above about a + + align:start position:0% +lateral pnps in particular above about a + + + align:start position:0% +lateral pnps in particular above about a +megahertz they look very much like time + + align:start position:0% +megahertz they look very much like time + + + align:start position:0% +megahertz they look very much like time +delays and we're not able to compensate + + align:start position:0% +delays and we're not able to compensate + + + align:start position:0% +delays and we're not able to compensate +as we recall for the phase shift + + align:start position:0% +as we recall for the phase shift + + + align:start position:0% +as we recall for the phase shift +associated with a pure time delay so we + + align:start position:0% +associated with a pure time delay so we + + + align:start position:0% +associated with a pure time delay so we +have to bear in mind when we're doing + + align:start position:0% +have to bear in mind when we're doing + + + align:start position:0% +have to bear in mind when we're doing +our compensation that any Loop that + + align:start position:0% +our compensation that any Loop that + + + align:start position:0% +our compensation that any Loop that +includes this kind of an amplifier the + + align:start position:0% +includes this kind of an amplifier the + + + align:start position:0% +includes this kind of an amplifier the +major Loop crossover is constrained to + + align:start position:0% +major Loop crossover is constrained to + + + align:start position:0% +major Loop crossover is constrained to +somewhere on the order of megahertz + + align:start position:0% +somewhere on the order of megahertz + + + align:start position:0% +somewhere on the order of megahertz +actually that's been getting a little + + align:start position:0% +actually that's been getting a little + + + align:start position:0% +actually that's been getting a little +bit better with time reflecting process + + align:start position:0% +bit better with time reflecting process + + + align:start position:0% +bit better with time reflecting process +improvements we'll see in the amplifier + + align:start position:0% +improvements we'll see in the amplifier + + + align:start position:0% +improvements we'll see in the amplifier +we we're using now uh we can get about 2 + + align:start position:0% +we we're using now uh we can get about 2 + + + align:start position:0% +we we're using now uh we can get about 2 +megahertz crossovers without too much + + align:start position:0% +megahertz crossovers without too much + + + align:start position:0% +megahertz crossovers without too much +trouble the quantity G subm over two + + align:start position:0% +trouble the quantity G subm over two + + + align:start position:0% +trouble the quantity G subm over two +which we mentioned last time enters into + + align:start position:0% +which we mentioned last time enters into + + + align:start position:0% +which we mentioned last time enters into +the approximation for the open loop + + align:start position:0% +the approximation for the open loop + + + align:start position:0% +the approximation for the open loop +transfer function of the amplifier is + + align:start position:0% +transfer function of the amplifier is + + + align:start position:0% +transfer function of the amplifier is +about 2 * 10us 4 Mo for this + + align:start position:0% +about 2 * 10us 4 Mo for this + + + align:start position:0% +about 2 * 10us 4 Mo for this +amplifier uh that reflects the fact that + + align:start position:0% +amplifier uh that reflects the fact that + + + align:start position:0% +amplifier uh that reflects the fact that +the input transistors are running at 10 + + align:start position:0% +the input transistors are running at 10 + + + align:start position:0% +the input transistors are running at 10 +microamp consequently the corresponding + + align:start position:0% +microamp consequently the corresponding + + + align:start position:0% +microamp consequently the corresponding +transconductance is about four time 10us + + align:start position:0% +transconductance is about four time 10us + + + align:start position:0% +transconductance is about four time 10us +4th modes there's again a manufacturing + + align:start position:0% +4th modes there's again a manufacturing + + + align:start position:0% +4th modes there's again a manufacturing +variation on that but a a nominal value + + align:start position:0% +variation on that but a a nominal value + + + align:start position:0% +variation on that but a a nominal value +for the trans conductance or the + + align:start position:0% +for the trans conductance or the + + + align:start position:0% +for the trans conductance or the +quantity G sub m/2 is about 2 * 10us 4 m + + align:start position:0% +quantity G sub m/2 is about 2 * 10us 4 m + + + align:start position:0% +quantity G sub m/2 is about 2 * 10us 4 m +a final thing that we didn't mention + + align:start position:0% +a final thing that we didn't mention + + + align:start position:0% +a final thing that we didn't mention +last time but will become important + + align:start position:0% +last time but will become important + + + align:start position:0% +last time but will become important +actually in the session that follows + + align:start position:0% +actually in the session that follows + + + align:start position:0% +actually in the session that follows +this one is that certain kinds of of + + align:start position:0% +this one is that certain kinds of of + + + align:start position:0% +this one is that certain kinds of of +monor loop compensation result in + + align:start position:0% +monor loop compensation result in + + + align:start position:0% +monor loop compensation result in +stability of problems associated with a + + align:start position:0% +stability of problems associated with a + + + align:start position:0% +stability of problems associated with a +minor Loop itself and so we have to be + + align:start position:0% +minor Loop itself and so we have to be + + + align:start position:0% +minor Loop itself and so we have to be +careful when we do the compensation in + + align:start position:0% +careful when we do the compensation in + + + align:start position:0% +careful when we do the compensation in +this system or in any other system that + + align:start position:0% +this system or in any other system that + + + align:start position:0% +this system or in any other system that +uses minor Loop compensation to make + + align:start position:0% +uses minor Loop compensation to make + + + align:start position:0% +uses minor Loop compensation to make +sure that the minor Loop remains + + align:start position:0% +sure that the minor Loop remains + + + align:start position:0% +sure that the minor Loop remains +acceptably + + align:start position:0% +acceptably + + + align:start position:0% +acceptably +stable one kind of compensation that we + + align:start position:0% +stable one kind of compensation that we + + + align:start position:0% +stable one kind of compensation that we +can Implement very easily in monor Loop + + align:start position:0% +can Implement very easily in monor Loop + + + align:start position:0% +can Implement very easily in monor Loop +form is so-called single pole + + align:start position:0% +form is so-called single pole + + + align:start position:0% +form is so-called single pole +compensation what we do there is use a + + align:start position:0% +compensation what we do there is use a + + + align:start position:0% +compensation what we do there is use a +single capacitor as the compensating + + align:start position:0% +single capacitor as the compensating + + + align:start position:0% +single capacitor as the compensating +element that's sort of a degenerate case + + align:start position:0% +element that's sort of a degenerate case + + + align:start position:0% +element that's sort of a degenerate case +of a two-port and if we go through the + + align:start position:0% +of a two-port and if we go through the + + + align:start position:0% +of a two-port and if we go through the +numbers we find out that the transfer + + align:start position:0% +numbers we find out that the transfer + + + align:start position:0% +numbers we find out that the transfer +admittance for a capacitor a single + + align:start position:0% +admittance for a capacitor a single + + + align:start position:0% +admittance for a capacitor a single +capacitor is simply equal to the value + + align:start position:0% +capacitor is simply equal to the value + + + align:start position:0% +capacitor is simply equal to the value +of the capacitance let's call it C subc + + align:start position:0% +of the capacitance let's call it C subc + + + align:start position:0% +of the capacitance let's call it C subc +Time s consequently when we evaluated + + align:start position:0% +Time s consequently when we evaluated + + + align:start position:0% +Time s consequently when we evaluated +our approximation to the open loop + + align:start position:0% +our approximation to the open loop + + + align:start position:0% +our approximation to the open loop +transfer function of the amplifier it + + align:start position:0% +transfer function of the amplifier it + + + align:start position:0% +transfer function of the amplifier it +would be G subm over 2 * C sub + + align:start position:0% + + + + align:start position:0% + +CS + + align:start position:0% + + + + align:start position:0% + +we can look at what we're trying to + + align:start position:0% +we can look at what we're trying to + + + align:start position:0% +we can look at what we're trying to +accomplish with this sort of + + align:start position:0% + + + + align:start position:0% + +compensation from remember from last + + align:start position:0% +compensation from remember from last + + + align:start position:0% +compensation from remember from last +time we mentioned that the way we + + align:start position:0% +time we mentioned that the way we + + + align:start position:0% +time we mentioned that the way we +determine the + + align:start position:0% +determine the + + + align:start position:0% +determine the +actual open loop transfer function of + + align:start position:0% +actual open loop transfer function of + + + align:start position:0% +actual open loop transfer function of +the amplifier with + + align:start position:0% +the amplifier with + + + align:start position:0% +the amplifier with +compensation is to First + + align:start position:0% +compensation is to First + + + align:start position:0% +compensation is to First +draw the uncompensated transfer function + + align:start position:0% +draw the uncompensated transfer function + + + align:start position:0% +draw the uncompensated transfer function +of the + + align:start position:0% +of the + + + align:start position:0% +of the +amplifier here I've assumed that our + + align:start position:0% +amplifier here I've assumed that our + + + align:start position:0% +amplifier here I've assumed that our +amplifier is actually three pole here's + + align:start position:0% +amplifier is actually three pole here's + + + align:start position:0% +amplifier is actually three pole here's +one pole Two Poles three poles but the + + align:start position:0% +one pole Two Poles three poles but the + + + align:start position:0% +one pole Two Poles three poles but the +details of this aren't important the + + align:start position:0% +details of this aren't important the + + + align:start position:0% +details of this aren't important the +point is we do have the uncompensated + + align:start position:0% +point is we do have the uncompensated + + + align:start position:0% +point is we do have the uncompensated +open loop transfer function of the + + align:start position:0% +open loop transfer function of the + + + align:start position:0% +open loop transfer function of the +amplifier that which would result if we + + align:start position:0% +amplifier that which would result if we + + + align:start position:0% +amplifier that which would result if we +disabled the compensating network but + + align:start position:0% +disabled the compensating network but + + + align:start position:0% +disabled the compensating network but +included its loading so that's this + + align:start position:0% +included its loading so that's this + + + align:start position:0% +included its loading so that's this +curve then we draw the + + align:start position:0% +curve then we draw the + + + align:start position:0% +curve then we draw the +approximation and in the case where we + + align:start position:0% +approximation and in the case where we + + + align:start position:0% +approximation and in the case where we +use a single capacitor we of course get + + align:start position:0% +use a single capacitor we of course get + + + align:start position:0% +use a single capacitor we of course get +a one pole approximation inversely + + align:start position:0% +a one pole approximation inversely + + + align:start position:0% +a one pole approximation inversely +proportional to + + align:start position:0% +proportional to + + + align:start position:0% +proportional to +s + + align:start position:0% +s + + + align:start position:0% +s +so here's the + + align:start position:0% +so here's the + + + align:start position:0% +so here's the +approximation then to a good degree of + + align:start position:0% +approximation then to a good degree of + + + align:start position:0% +approximation then to a good degree of +approximation why our overall + + align:start position:0% +approximation why our overall + + + align:start position:0% +approximation why our overall +compensated open loop transfer function + + align:start position:0% +compensated open loop transfer function + + + align:start position:0% +compensated open loop transfer function +for the amplifier is simply the lower of + + align:start position:0% +for the amplifier is simply the lower of + + + align:start position:0% +for the amplifier is simply the lower of +these two curves at all + + align:start position:0% +these two curves at all + + + align:start position:0% +these two curves at all +frequencies we've showed some dotted + + align:start position:0% +frequencies we've showed some dotted + + + align:start position:0% +frequencies we've showed some dotted +lines here over a range of frequencies + + align:start position:0% +lines here over a range of frequencies + + + align:start position:0% +lines here over a range of frequencies +where the open loop transfer function of + + align:start position:0% +where the open loop transfer function of + + + align:start position:0% +where the open loop transfer function of +the operational amplifier is in fact + + align:start position:0% +the operational amplifier is in fact + + + align:start position:0% +the operational amplifier is in fact +controlled by minor Loop feedback + + align:start position:0% +controlled by minor Loop feedback + + + align:start position:0% +controlled by minor Loop feedback +remember the inequalities between the + + align:start position:0% +remember the inequalities between the + + + align:start position:0% +remember the inequalities between the +uncompensated transfer function and the + + align:start position:0% +uncompensated transfer function and the + + + align:start position:0% +uncompensated transfer function and the +approximation involving the transfer + + align:start position:0% +approximation involving the transfer + + + align:start position:0% +approximation involving the transfer +admittance of the compensating element + + align:start position:0% +admittance of the compensating element + + + align:start position:0% +admittance of the compensating element +are such that in this region the + + align:start position:0% +are such that in this region the + + + align:start position:0% +are such that in this region the +amplifier open loop performance is very + + align:start position:0% +amplifier open loop performance is very + + + align:start position:0% +amplifier open loop performance is very +directly controlled by minor Loop + + align:start position:0% +directly controlled by minor Loop + + + align:start position:0% +directly controlled by minor Loop +compensation and so over this range of + + align:start position:0% +compensation and so over this range of + + + align:start position:0% +compensation and so over this range of +frequencies we can estimate the open + + align:start position:0% +frequencies we can estimate the open + + + align:start position:0% +frequencies we can estimate the open +loop transfer function of the amplifier + + align:start position:0% +loop transfer function of the amplifier + + + align:start position:0% +loop transfer function of the amplifier +based only on a knowledge of its of the + + align:start position:0% +based only on a knowledge of its of the + + + align:start position:0% +based only on a knowledge of its of the +transconductance of its first stage Ag + + align:start position:0% +transconductance of its first stage Ag + + + align:start position:0% +transconductance of its first stage Ag +and the compensating element that we're + + align:start position:0% +and the compensating element that we're + + + align:start position:0% +and the compensating element that we're +using in this case a + + align:start position:0% +using in this case a + + + align:start position:0% +using in this case a +capacitor the effect on the angle + + align:start position:0% +capacitor the effect on the angle + + + align:start position:0% +capacitor the effect on the angle +associated with the open loop transfer + + align:start position:0% +associated with the open loop transfer + + + align:start position:0% +associated with the open loop transfer +function is shown below uh here we have + + align:start position:0% +function is shown below uh here we have + + + align:start position:0% +function is shown below uh here we have +the original uncompensated for transfer + + align:start position:0% +the original uncompensated for transfer + + + align:start position:0% +the original uncompensated for transfer +function assumed to be three pole but + + align:start position:0% +function assumed to be three pole but + + + align:start position:0% +function assumed to be three pole but +again that's that's not horribly + + align:start position:0% +again that's that's not horribly + + + align:start position:0% +again that's that's not horribly +important the effect of adding the + + align:start position:0% +important the effect of adding the + + + align:start position:0% +important the effect of adding the +compensation the single pole + + align:start position:0% +compensation the single pole + + + align:start position:0% +compensation the single pole +compensation is to force a single pole + + align:start position:0% +compensation is to force a single pole + + + align:start position:0% +compensation is to force a single pole +rollof between this frequency and some + + align:start position:0% +rollof between this frequency and some + + + align:start position:0% +rollof between this frequency and some +much higher frequency and so we have a + + align:start position:0% +much higher frequency and so we have a + + + align:start position:0% +much higher frequency and so we have a +long range of frequencies here where the + + align:start position:0% +long range of frequencies here where the + + + align:start position:0% +long range of frequencies here where the +amplifier open loop transfer function is + + align:start position:0% +amplifier open loop transfer function is + + + align:start position:0% +amplifier open loop transfer function is +in fact following a single pole roll off + + align:start position:0% +in fact following a single pole roll off + + + align:start position:0% +in fact following a single pole roll off +we get approximately 90° of phase shift + + align:start position:0% +we get approximately 90° of phase shift + + + align:start position:0% +we get approximately 90° of phase shift +so here we have a situation where the + + align:start position:0% +so here we have a situation where the + + + align:start position:0% +so here we have a situation where the +use of a single capacitor and in fact + + align:start position:0% +use of a single capacitor and in fact + + + align:start position:0% +use of a single capacitor and in fact +quite a small one as we see controls the + + align:start position:0% +quite a small one as we see controls the + + + align:start position:0% +quite a small one as we see controls the +transfer function over a very wide range + + align:start position:0% +transfer function over a very wide range + + + align:start position:0% +transfer function over a very wide range +of frequencies and in fact gives us an + + align:start position:0% +of frequencies and in fact gives us an + + + align:start position:0% +of frequencies and in fact gives us an +approximately single pole rolloff over a + + align:start position:0% +approximately single pole rolloff over a + + + align:start position:0% +approximately single pole rolloff over a +very wide range of + + align:start position:0% +very wide range of + + + align:start position:0% +very wide range of +frequencies + + align:start position:0% + + + + align:start position:0% + +a frequently used value when we design + + align:start position:0% +a frequently used value when we design + + + align:start position:0% +a frequently used value when we design +an amplifier that includes internal + + align:start position:0% +an amplifier that includes internal + + + align:start position:0% +an amplifier that includes internal +compensation rather than one where we + + align:start position:0% +compensation rather than one where we + + + align:start position:0% +compensation rather than one where we +can add the compensation ourselves an + + align:start position:0% +can add the compensation ourselves an + + + align:start position:0% +can add the compensation ourselves an +amplifier such as a 741 as I mentioned + + align:start position:0% +amplifier such as a 741 as I mentioned + + + align:start position:0% +amplifier such as a 741 as I mentioned +last time is one that uses this General + + align:start position:0% +last time is one that uses this General + + + align:start position:0% +last time is one that uses this General +topology the general two-stage topology + + align:start position:0% +topology the general two-stage topology + + + align:start position:0% +topology the general two-stage topology +but it has an internal capacitor and the + + align:start position:0% +but it has an internal capacitor and the + + + align:start position:0% +but it has an internal capacitor and the +value of that capacitor is typically 30 + + align:start position:0% +value of that capacitor is typically 30 + + + align:start position:0% +value of that capacitor is typically 30 +paaf + + align:start position:0% +paaf + + + align:start position:0% +paaf +farads the transconductance of 74 41 + + align:start position:0% +farads the transconductance of 74 41 + + + align:start position:0% +farads the transconductance of 74 41 +input transistor is the same as for for + + align:start position:0% +input transistor is the same as for for + + + align:start position:0% +input transistor is the same as for for +the 101a and consequently the quantity G + + align:start position:0% +the 101a and consequently the quantity G + + + align:start position:0% +the 101a and consequently the quantity G +subm / 2 * C sub CS is equal to G subm / + + align:start position:0% +subm / 2 * C sub CS is equal to G subm / + + + align:start position:0% +subm / 2 * C sub CS is equal to G subm / +2 or 2 * 10- 4 Moses divided 3 * 10- + + align:start position:0% +2 or 2 * 10- 4 Moses divided 3 * 10- + + + align:start position:0% +2 or 2 * 10- 4 Moses divided 3 * 10- +11th farads in the case of a 30 paa + + align:start position:0% +11th farads in the case of a 30 paa + + + align:start position:0% +11th farads in the case of a 30 paa +farad capacitor and then thus our + + align:start position:0% +farad capacitor and then thus our + + + align:start position:0% +farad capacitor and then thus our +approximation to the open loop transfer + + align:start position:0% +approximation to the open loop transfer + + + align:start position:0% +approximation to the open loop transfer +function is about 6.7 * 10 6/ + + align:start position:0% +function is about 6.7 * 10 6/ + + + align:start position:0% +function is about 6.7 * 10 6/ +s that transfer function actually holds + + align:start position:0% +s that transfer function actually holds + + + align:start position:0% +s that transfer function actually holds +over a range of frequencies that + + align:start position:0% +over a range of frequencies that + + + align:start position:0% +over a range of frequencies that +typically extends from about 10 Hertz to + + align:start position:0% +typically extends from about 10 Hertz to + + + align:start position:0% +typically extends from about 10 Hertz to +roughly a megahertz so here a 30 paa + + align:start position:0% +roughly a megahertz so here a 30 paa + + + align:start position:0% +roughly a megahertz so here a 30 paa +farad capacitor compensates the + + align:start position:0% +farad capacitor compensates the + + + align:start position:0% +farad capacitor compensates the +amplifier dominates its performance over + + align:start position:0% +amplifier dominates its performance over + + + align:start position:0% +amplifier dominates its performance over +about a factor of 10 5th to one in + + align:start position:0% +about a factor of 10 5th to one in + + + align:start position:0% +about a factor of 10 5th to one in +frequency that's very significant + + align:start position:0% +frequency that's very significant + + + align:start position:0% +frequency that's very significant +actually for the fabrication of + + align:start position:0% +actually for the fabrication of + + + align:start position:0% +actually for the fabrication of +integrated circuits because using this + + align:start position:0% +integrated circuits because using this + + + align:start position:0% +integrated circuits because using this +minor Loop technique in the topology + + align:start position:0% +minor Loop technique in the topology + + + align:start position:0% +minor Loop technique in the topology +we've discussed we're able to compensate + + align:start position:0% +we've discussed we're able to compensate + + + align:start position:0% +we've discussed we're able to compensate +the amplifier with a size capacitor that + + align:start position:0% +the amplifier with a size capacitor that + + + align:start position:0% +the amplifier with a size capacitor that +can be fitted onto the onto the chip it + + align:start position:0% +can be fitted onto the onto the chip it + + + align:start position:0% +can be fitted onto the onto the chip it +doesn't consume excessive chip area and + + align:start position:0% +doesn't consume excessive chip area and + + + align:start position:0% +doesn't consume excessive chip area and +so one of the things that made internal + + align:start position:0% +so one of the things that made internal + + + align:start position:0% +so one of the things that made internal +compensation of operational amplifiers + + align:start position:0% +compensation of operational amplifiers + + + align:start position:0% +compensation of operational amplifiers +possible was exploitation of this sort + + align:start position:0% +possible was exploitation of this sort + + + align:start position:0% +possible was exploitation of this sort +of minor Loop + + align:start position:0% +of minor Loop + + + align:start position:0% +of minor Loop +topology the reason for the choice of a + + align:start position:0% +topology the reason for the choice of a + + + align:start position:0% +topology the reason for the choice of a +30 peared capacitor and fixed + + align:start position:0% +30 peared capacitor and fixed + + + align:start position:0% +30 peared capacitor and fixed +compensation amplifiers is that that + + align:start position:0% +compensation amplifiers is that that + + + align:start position:0% +compensation amplifiers is that that +forces crossover in other words we we go + + align:start position:0% +forces crossover in other words we we go + + + align:start position:0% +forces crossover in other words we we go +through Unity gain in the amplifier for + + align:start position:0% +through Unity gain in the amplifier for + + + align:start position:0% +through Unity gain in the amplifier for +the amplifier open loop transfer + + align:start position:0% +the amplifier open loop transfer + + + align:start position:0% +the amplifier open loop transfer +function at a frequency of course of 6.7 + + align:start position:0% +function at a frequency of course of 6.7 + + + align:start position:0% +function at a frequency of course of 6.7 +time 10 6 radians per second or about a + + align:start position:0% +time 10 6 radians per second or about a + + + align:start position:0% +time 10 6 radians per second or about a +megahertz and uh we mentioned that the + + align:start position:0% +megahertz and uh we mentioned that the + + + align:start position:0% +megahertz and uh we mentioned that the +phase shift problems associated with the + + align:start position:0% +phase shift problems associated with the + + + align:start position:0% +phase shift problems associated with the +Dynamics of the PNP transistors that are + + align:start position:0% +Dynamics of the PNP transistors that are + + + align:start position:0% +Dynamics of the PNP transistors that are +typically used in this topology are such + + align:start position:0% +typically used in this topology are such + + + align:start position:0% +typically used in this topology are such +that we have to constrain crossover to + + align:start position:0% +that we have to constrain crossover to + + + align:start position:0% +that we have to constrain crossover to +about a megahertz or else we'll get + + align:start position:0% +about a megahertz or else we'll get + + + align:start position:0% +about a megahertz or else we'll get +stability problems so this amplifier one + + align:start position:0% +stability problems so this amplifier one + + + align:start position:0% +stability problems so this amplifier one +that uses a 30 peaka farad capacitor is + + align:start position:0% +that uses a 30 peaka farad capacitor is + + + align:start position:0% +that uses a 30 peaka farad capacitor is +an example of one that will be Unity + + align:start position:0% +an example of one that will be Unity + + + align:start position:0% +an example of one that will be Unity +gain stable in other words if we form a + + align:start position:0% +gain stable in other words if we form a + + + align:start position:0% +gain stable in other words if we form a +feedback loop with f equal to 1 by + + align:start position:0% +feedback loop with f equal to 1 by + + + align:start position:0% +feedback loop with f equal to 1 by +connecting the output of the amplifier + + align:start position:0% +connecting the output of the amplifier + + + align:start position:0% +connecting the output of the amplifier +directly back to its input the resultant + + align:start position:0% +directly back to its input the resultant + + + align:start position:0% +directly back to its input the resultant +configuration should be stable since the + + align:start position:0% +configuration should be stable since the + + + align:start position:0% +configuration should be stable since the +major Loop thus formed crosses over at + + align:start position:0% +major Loop thus formed crosses over at + + + align:start position:0% +major Loop thus formed crosses over at +about a + + align:start position:0% +about a + + + align:start position:0% +about a +megahertz the problem is that that sort + + align:start position:0% +megahertz the problem is that that sort + + + align:start position:0% +megahertz the problem is that that sort +of compensation is overly conservative + + align:start position:0% +of compensation is overly conservative + + + align:start position:0% +of compensation is overly conservative +in many applications it's fine if we + + align:start position:0% +in many applications it's fine if we + + + align:start position:0% +in many applications it's fine if we +have direct feedback from the output to + + align:start position:0% +have direct feedback from the output to + + + align:start position:0% +have direct feedback from the output to +the input but it really deteriorates the + + align:start position:0% +the input but it really deteriorates the + + + align:start position:0% +the input but it really deteriorates the +dynamic performance in many many other + + align:start position:0% +dynamic performance in many many other + + + align:start position:0% +dynamic performance in many many other +feedback + + align:start position:0% +feedback + + + align:start position:0% +feedback +configurations let's consider the + + align:start position:0% +configurations let's consider the + + + align:start position:0% +configurations let's consider the +following here we have an operational + + align:start position:0% +following here we have an operational + + + align:start position:0% +following here we have an operational +amplifier + + align:start position:0% +amplifier + + + align:start position:0% +amplifier +connected as a non-inverting amplifier + + align:start position:0% +connected as a non-inverting amplifier + + + align:start position:0% +connected as a non-inverting amplifier +of course we've seen this configuration + + align:start position:0% +of course we've seen this configuration + + + align:start position:0% +of course we've seen this configuration +before we have attenuation from the + + align:start position:0% +before we have attenuation from the + + + align:start position:0% +before we have attenuation from the +output back to the inverting input via + + align:start position:0% +output back to the inverting input via + + + align:start position:0% +output back to the inverting input via +the R1 R2 network uh we have a single + + align:start position:0% +the R1 R2 network uh we have a single + + + align:start position:0% +the R1 R2 network uh we have a single +capacitor that's used for compensation + + align:start position:0% +capacitor that's used for compensation + + + align:start position:0% +capacitor that's used for compensation +and I'd like to investigate that + + align:start position:0% + + + + align:start position:0% + +configuration the block diagram assuming + + align:start position:0% +configuration the block diagram assuming + + + align:start position:0% +configuration the block diagram assuming +that we can represent the amplifier by + + align:start position:0% +that we can represent the amplifier by + + + align:start position:0% +that we can represent the amplifier by +our approximation has a forward path + + align:start position:0% +our approximation has a forward path + + + align:start position:0% +our approximation has a forward path +that will be simply the approximation G + + align:start position:0% +that will be simply the approximation G + + + align:start position:0% +that will be simply the approximation G +subm over 2 time C sub + + align:start position:0% +subm over 2 time C sub + + + align:start position:0% +subm over 2 time C sub +CS the feedback path reflects the + + align:start position:0% +CS the feedback path reflects the + + + align:start position:0% +CS the feedback path reflects the +attenuation provided by the R1 R1 plus + + align:start position:0% +attenuation provided by the R1 R1 plus + + + align:start position:0% +attenuation provided by the R1 R1 plus +R2 + + align:start position:0% +R2 + + + align:start position:0% +R2 +network if we estimate the closed loop + + align:start position:0% +network if we estimate the closed loop + + + align:start position:0% +network if we estimate the closed loop +gain based on this expression for the + + align:start position:0% +gain based on this expression for the + + + align:start position:0% +gain based on this expression for the +forward path gain we get the expression + + align:start position:0% +forward path gain we get the expression + + + align:start position:0% +forward path gain we get the expression +shown G subm / 2 C sub CS 1 + G subm / 2 + + align:start position:0% +shown G subm / 2 C sub CS 1 + G subm / 2 + + + align:start position:0% +shown G subm / 2 C sub CS 1 + G subm / 2 +CCS * f 1 minus the loop transmission + + align:start position:0% +CCS * f 1 minus the loop transmission + + + align:start position:0% +CCS * f 1 minus the loop transmission +assuming that the uh loop transmission + + align:start position:0% +assuming that the uh loop transmission + + + align:start position:0% +assuming that the uh loop transmission +can use this estimate for the forward + + align:start position:0% +can use this estimate for the forward + + + align:start position:0% +can use this estimate for the forward +path gain and if we rearrange terms + + align:start position:0% +path gain and if we rearrange terms + + + align:start position:0% +path gain and if we rearrange terms +basically multiply numerator and + + align:start position:0% +basically multiply numerator and + + + align:start position:0% +basically multiply numerator and +denominator by the reciprocal of the + + align:start position:0% +denominator by the reciprocal of the + + + align:start position:0% +denominator by the reciprocal of the +second term in the denominator we find + + align:start position:0% +second term in the denominator we find + + + align:start position:0% +second term in the denominator we find +out that the closed loop gain is single + + align:start position:0% +out that the closed loop gain is single + + + align:start position:0% +out that the closed loop gain is single +pole has a value 1/ F the ideal closed + + align:start position:0% +pole has a value 1/ F the ideal closed + + + align:start position:0% +pole has a value 1/ F the ideal closed +loop gain which results at low + + align:start position:0% +loop gain which results at low + + + align:start position:0% +loop gain which results at low +frequencies uh and then a single pole + + align:start position:0% +frequencies uh and then a single pole + + + align:start position:0% +frequencies uh and then a single pole +rollof where the time constant + + align:start position:0% +rollof where the time constant + + + align:start position:0% +rollof where the time constant +associated with that roll off is related + + align:start position:0% +associated with that roll off is related + + + align:start position:0% +associated with that roll off is related +to the ratio of c subc and and + + align:start position:0% +to the ratio of c subc and and + + + align:start position:0% +to the ratio of c subc and and +F now the problem is that as we go to + + align:start position:0% +F now the problem is that as we go to + + + align:start position:0% +F now the problem is that as we go to +larger and larger closed loop gains in + + align:start position:0% +larger and larger closed loop gains in + + + align:start position:0% +larger and larger closed loop gains in +other words if we go back to our + + align:start position:0% +other words if we go back to our + + + align:start position:0% +other words if we go back to our +original + + align:start position:0% +original + + + align:start position:0% +original +amplifier and in order to get higher + + align:start position:0% +amplifier and in order to get higher + + + align:start position:0% +amplifier and in order to get higher +close close loop gains of course we'd + + align:start position:0% +close close loop gains of course we'd + + + align:start position:0% +close close loop gains of course we'd +make R1 smaller relative to R2 thereby + + align:start position:0% +make R1 smaller relative to R2 thereby + + + align:start position:0% +make R1 smaller relative to R2 thereby +lowering F and since the ideal Clos Loop + + align:start position:0% +lowering F and since the ideal Clos Loop + + + align:start position:0% +lowering F and since the ideal Clos Loop +gain for this non-inverting + + align:start position:0% +gain for this non-inverting + + + align:start position:0% +gain for this non-inverting +configuration is of course simply 1 over + + align:start position:0% +configuration is of course simply 1 over + + + align:start position:0% +configuration is of course simply 1 over +F why as we lower that ratio we make F + + align:start position:0% +F why as we lower that ratio we make F + + + align:start position:0% +F why as we lower that ratio we make F +smaller we get progressively higher + + align:start position:0% +smaller we get progressively higher + + + align:start position:0% +smaller we get progressively higher +closed loop gains the problem is that + + align:start position:0% +closed loop gains the problem is that + + + align:start position:0% +closed loop gains the problem is that +for a fixed value of compensating + + align:start position:0% +for a fixed value of compensating + + + align:start position:0% +for a fixed value of compensating +capacitor if C subc is fixed why + + align:start position:0% +capacitor if C subc is fixed why + + + align:start position:0% +capacitor if C subc is fixed why +the as we lower F the time con + + align:start position:0% +the as we lower F the time con + + + align:start position:0% +the as we lower F the time con +associated with the closed loop pole + + align:start position:0% +associated with the closed loop pole + + + align:start position:0% +associated with the closed loop pole +gets progressively larger in other words + + align:start position:0% +gets progressively larger in other words + + + align:start position:0% +gets progressively larger in other words +the amplifier gets slower as we go to + + align:start position:0% +the amplifier gets slower as we go to + + + align:start position:0% +the amplifier gets slower as we go to +larger and larger closed loop gains + + align:start position:0% +larger and larger closed loop gains + + + align:start position:0% +larger and larger closed loop gains +however consider what happens if as we + + align:start position:0% +however consider what happens if as we + + + align:start position:0% +however consider what happens if as we +change F we modify C subc we change C + + align:start position:0% +change F we modify C subc we change C + + + align:start position:0% +change F we modify C subc we change C +subc in about a proportionate way and if + + align:start position:0% +subc in about a proportionate way and if + + + align:start position:0% +subc in about a proportionate way and if +we do that why we can keep the Dynamics + + align:start position:0% +we do that why we can keep the Dynamics + + + align:start position:0% +we do that why we can keep the Dynamics +the closed loop Dynamics fairly constant + + align:start position:0% +the closed loop Dynamics fairly constant + + + align:start position:0% +the closed loop Dynamics fairly constant +we can again look at the effect of that + + align:start position:0% +we can again look at the effect of that + + + align:start position:0% +we can again look at the effect of that +on one of our earlier view + + align:start position:0% + + + + align:start position:0% + +graphs this is the curve that is g subm + + align:start position:0% +graphs this is the curve that is g subm + + + align:start position:0% +graphs this is the curve that is g subm +over 2 * c subc s as we change the value + + align:start position:0% +over 2 * c subc s as we change the value + + + align:start position:0% +over 2 * c subc s as we change the value +of C subc to larger values the curve + + align:start position:0% +of C subc to larger values the curve + + + align:start position:0% +of C subc to larger values the curve +moves down as we decrease the value of C + + align:start position:0% +moves down as we decrease the value of C + + + align:start position:0% +moves down as we decrease the value of C +subc the curve moves up implying wider + + align:start position:0% +subc the curve moves up implying wider + + + align:start position:0% +subc the curve moves up implying wider +bandwidth out of the amplifier itself + + align:start position:0% +bandwidth out of the amplifier itself + + + align:start position:0% +bandwidth out of the amplifier itself +now as we decrease C subc the unity gain + + align:start position:0% +now as we decrease C subc the unity gain + + + align:start position:0% +now as we decrease C subc the unity gain +frequency of the amplifier + + align:start position:0% +frequency of the amplifier + + + align:start position:0% +frequency of the amplifier +itself will increase and in fact may + + align:start position:0% +itself will increase and in fact may + + + align:start position:0% +itself will increase and in fact may +very easily become a go above a + + align:start position:0% +very easily become a go above a + + + align:start position:0% +very easily become a go above a +megahertz for certain values of c subc + + align:start position:0% +megahertz for certain values of c subc + + + align:start position:0% +megahertz for certain values of c subc +in fact if C subc is less than about 30 + + align:start position:0% +in fact if C subc is less than about 30 + + + align:start position:0% +in fact if C subc is less than about 30 +picarats the unity gain frequency of the + + align:start position:0% +picarats the unity gain frequency of the + + + align:start position:0% +picarats the unity gain frequency of the +amplifier + + align:start position:0% +amplifier + + + align:start position:0% +amplifier +itself extends Beyond a megahertz that's + + align:start position:0% +itself extends Beyond a megahertz that's + + + align:start position:0% +itself extends Beyond a megahertz that's +no problem though if F gets + + align:start position:0% +no problem though if F gets + + + align:start position:0% +no problem though if F gets +correspondingly smaller since the + + align:start position:0% +correspondingly smaller since the + + + align:start position:0% +correspondingly smaller since the +crossover frequency of the major Loop is + + align:start position:0% +crossover frequency of the major Loop is + + + align:start position:0% +crossover frequency of the major Loop is +the one one we have to worry about in in + + align:start position:0% +the one one we have to worry about in in + + + align:start position:0% +the one one we have to worry about in in +terms of of loop stability problem so + + align:start position:0% +terms of of loop stability problem so + + + align:start position:0% +terms of of loop stability problem so +here as we lower F we can make + + align:start position:0% +here as we lower F we can make + + + align:start position:0% +here as we lower F we can make +corresponding changes in C subc the + + align:start position:0% +corresponding changes in C subc the + + + align:start position:0% +corresponding changes in C subc the +overall major Loop still crosses over at + + align:start position:0% +overall major Loop still crosses over at + + + align:start position:0% +overall major Loop still crosses over at +frequencies of of about a megahertz or + + align:start position:0% +frequencies of of about a megahertz or + + + align:start position:0% +frequencies of of about a megahertz or +so and so we don't get into stability + + align:start position:0% +so and so we don't get into stability + + + align:start position:0% +so and so we don't get into stability +problems because of the lateral PNP + + align:start position:0% +problems because of the lateral PNP + + + align:start position:0% +problems because of the lateral PNP +transistors let's see how this works in + + align:start position:0% + + + + align:start position:0% + +practice here we have a a board that + + align:start position:0% +practice here we have a a board that + + + align:start position:0% +practice here we have a a board that +includes an amplifier where we can + + align:start position:0% +includes an amplifier where we can + + + align:start position:0% +includes an amplifier where we can +change the compensating element and the + + align:start position:0% +change the compensating element and the + + + align:start position:0% +change the compensating element and the +rest of the equipment then includes a + + align:start position:0% +rest of the equipment then includes a + + + align:start position:0% +rest of the equipment then includes a +power supply which simply Powers the + + align:start position:0% +power supply which simply Powers the + + + align:start position:0% +power supply which simply Powers the +amplifier in question a signal generator + + align:start position:0% +amplifier in question a signal generator + + + align:start position:0% +amplifier in question a signal generator +that allows us to put steps or other + + align:start position:0% +that allows us to put steps or other + + + align:start position:0% +that allows us to put steps or other +test signals into the amplifier and an + + align:start position:0% +test signals into the amplifier and an + + + align:start position:0% +test signals into the amplifier and an +oscilloscope to look at the resultant + + align:start position:0% +oscilloscope to look at the resultant + + + align:start position:0% +oscilloscope to look at the resultant +responses if we examine this board in + + align:start position:0% +responses if we examine this board in + + + align:start position:0% +responses if we examine this board in +detail it has more than we're actually + + align:start position:0% +detail it has more than we're actually + + + align:start position:0% +detail it has more than we're actually +actually going to use in this + + align:start position:0% +actually going to use in this + + + align:start position:0% +actually going to use in this +demonstration we're actually just using + + align:start position:0% +demonstration we're actually just using + + + align:start position:0% +demonstration we're actually just using +this little corner of it here is a 301a + + align:start position:0% +this little corner of it here is a 301a + + + align:start position:0% +this little corner of it here is a 301a +type operation amplifier right here + + align:start position:0% +type operation amplifier right here + + + align:start position:0% +type operation amplifier right here +there are two terminals uh on that + + align:start position:0% +there are two terminals uh on that + + + align:start position:0% +there are two terminals uh on that +amplifier here and here that are + + align:start position:0% +amplifier here and here that are + + + align:start position:0% +amplifier here and here that are +connected to the compensating or that + + align:start position:0% +connected to the compensating or that + + + align:start position:0% +connected to the compensating or that +allow us to connect the compensating + + align:start position:0% +allow us to connect the compensating + + + align:start position:0% +allow us to connect the compensating +element to the amplifier we're presently + + align:start position:0% +element to the amplifier we're presently + + + align:start position:0% +element to the amplifier we're presently +using a single capacitor for + + align:start position:0% +using a single capacitor for + + + align:start position:0% +using a single capacitor for +compensation as I mentioned single pole + + align:start position:0% +compensation as I mentioned single pole + + + align:start position:0% +compensation as I mentioned single pole +compensation here is that compensating + + align:start position:0% + + + + align:start position:0% + +capacitor in this particular amplifier + + align:start position:0% +capacitor in this particular amplifier + + + align:start position:0% +capacitor in this particular amplifier +or with this particular amplifier we + + align:start position:0% +or with this particular amplifier we + + + align:start position:0% +or with this particular amplifier we +found that we get very nice stable + + align:start position:0% +found that we get very nice stable + + + align:start position:0% +found that we get very nice stable +responses with just a small amount of + + align:start position:0% +responses with just a small amount of + + + align:start position:0% +responses with just a small amount of +overshoot as presently shown on the + + align:start position:0% +overshoot as presently shown on the + + + align:start position:0% +overshoot as presently shown on the +oscilloscope in unity feedback + + align:start position:0% +oscilloscope in unity feedback + + + align:start position:0% +oscilloscope in unity feedback +configurations when we use actually a + + align:start position:0% +configurations when we use actually a + + + align:start position:0% +configurations when we use actually a +20pa farad capacitor also if we look at + + align:start position:0% +20pa farad capacitor also if we look at + + + align:start position:0% +20pa farad capacitor also if we look at +the transconductance of this amplifier + + align:start position:0% +the transconductance of this amplifier + + + align:start position:0% +the transconductance of this amplifier +we find it's a little bit higher than + + align:start position:0% +we find it's a little bit higher than + + + align:start position:0% +we find it's a little bit higher than +the nominal value cross over with a 20pa + + align:start position:0% +the nominal value cross over with a 20pa + + + align:start position:0% +the nominal value cross over with a 20pa +farad capacitor or the unity gain + + align:start position:0% +farad capacitor or the unity gain + + + align:start position:0% +farad capacitor or the unity gain +frequency with a 20 peaf farad capacitor + + align:start position:0% +frequency with a 20 peaf farad capacitor + + + align:start position:0% +frequency with a 20 peaf farad capacitor +is actually about 2 megahertz in this + + align:start position:0% +is actually about 2 megahertz in this + + + align:start position:0% +is actually about 2 megahertz in this +particular amplifier the switches on the + + align:start position:0% +particular amplifier the switches on the + + + align:start position:0% +particular amplifier the switches on the +front of the Box in particular these two + + align:start position:0% +front of the Box in particular these two + + + align:start position:0% +front of the Box in particular these two +switches uh allow us to change F thereby + + align:start position:0% +switches uh allow us to change F thereby + + + align:start position:0% +switches uh allow us to change F thereby +establishing different values for the + + align:start position:0% +establishing different values for the + + + align:start position:0% +establishing different values for the +ideal closed loop gain right now we're + + align:start position:0% +ideal closed loop gain right now we're + + + align:start position:0% +ideal closed loop gain right now we're +set up for a closed loop gain of one + + align:start position:0% +set up for a closed loop gain of one + + + align:start position:0% +set up for a closed loop gain of one +with f equals 1 as I mentioned earlier + + align:start position:0% +with f equals 1 as I mentioned earlier + + + align:start position:0% +with f equals 1 as I mentioned earlier +we have the 20 peaka farad + + align:start position:0% +we have the 20 peaka farad + + + align:start position:0% +we have the 20 peaka farad +capacitor and we're looking at the + + align:start position:0% +capacitor and we're looking at the + + + align:start position:0% +capacitor and we're looking at the +resultant step response the horizontal + + align:start position:0% +resultant step response the horizontal + + + align:start position:0% +resultant step response the horizontal +scale is 100 nond per Division and one + + align:start position:0% +scale is 100 nond per Division and one + + + align:start position:0% +scale is 100 nond per Division and one +very good measure of speed of response + + align:start position:0% +very good measure of speed of response + + + align:start position:0% +very good measure of speed of response +of course which is easily interpreted in + + align:start position:0% +of course which is easily interpreted in + + + align:start position:0% +of course which is easily interpreted in +terms of bandwidth is the 10 to 90% rise + + align:start position:0% +terms of bandwidth is the 10 to 90% rise + + + align:start position:0% +terms of bandwidth is the 10 to 90% rise +time for the system uh so let's see here + + align:start position:0% +time for the system uh so let's see here + + + align:start position:0% +time for the system uh so let's see here +is the 10% point up here is the 90% + + align:start position:0% +is the 10% point up here is the 90% + + + align:start position:0% +is the 10% point up here is the 90% +Point uh we have just about one and a + + align:start position:0% +Point uh we have just about one and a + + + align:start position:0% +Point uh we have just about one and a +half divisions horizontally between + + align:start position:0% +half divisions horizontally between + + + align:start position:0% +half divisions horizontally between +those two points we're at 100 NCS per + + align:start position:0% +those two points we're at 100 NCS per + + + align:start position:0% +those two points we're at 100 NCS per +Division and so we have a rise time of + + align:start position:0% +Division and so we have a rise time of + + + align:start position:0% +Division and so we have a rise time of +about 150 Nan + + align:start position:0% + + + + align:start position:0% + +seconds so let's tabulate values here + + align:start position:0% +seconds so let's tabulate values here + + + align:start position:0% +seconds so let's tabulate values here +we're running at an ideal Clos Loop gain + + align:start position:0% +we're running at an ideal Clos Loop gain + + + align:start position:0% +we're running at an ideal Clos Loop gain +or a low frequency gain a KN which is + + align:start position:0% +or a low frequency gain a KN which is + + + align:start position:0% +or a low frequency gain a KN which is +equal to 1 over F we're running uh at a + + align:start position:0% +equal to 1 over F we're running uh at a + + + align:start position:0% +equal to 1 over F we're running uh at a +Clos Loop gain of one for this + + align:start position:0% +Clos Loop gain of one for this + + + align:start position:0% +Clos Loop gain of one for this +particular part of the demonstration and + + align:start position:0% +particular part of the demonstration and + + + align:start position:0% +particular part of the demonstration and +the rise time that we measure is about + + align:start position:0% +the rise time that we measure is about + + + align:start position:0% +the rise time that we measure is about +150 NCS we're using a 20 pea farad + + align:start position:0% +150 NCS we're using a 20 pea farad + + + align:start position:0% +150 NCS we're using a 20 pea farad +capacitor when we make that + + align:start position:0% +capacitor when we make that + + + align:start position:0% +capacitor when we make that +measurement for Unity feedback for an of + + align:start position:0% +measurement for Unity feedback for an of + + + align:start position:0% +measurement for Unity feedback for an of +one the optimum value of the capacitor + + align:start position:0% +one the optimum value of the capacitor + + + align:start position:0% +one the optimum value of the capacitor +is close to the 20 paa farad value going + + align:start position:0% +is close to the 20 paa farad value going + + + align:start position:0% +is close to the 20 paa farad value going +to smaller values of capacitor in in + + align:start position:0% +to smaller values of capacitor in in + + + align:start position:0% +to smaller values of capacitor in in +this with this value of f would result + + align:start position:0% +this with this value of f would result + + + align:start position:0% +this with this value of f would result +in progressively more overshoot + + align:start position:0% +in progressively more overshoot + + + align:start position:0% +in progressively more overshoot +progressively poorer stability uh + + align:start position:0% +progressively poorer stability uh + + + align:start position:0% +progressively poorer stability uh +because we'd be pushing the crossover of + + align:start position:0% +because we'd be pushing the crossover of + + + align:start position:0% +because we'd be pushing the crossover of +the major Loop out toward higher + + align:start position:0% +the major Loop out toward higher + + + align:start position:0% +the major Loop out toward higher +frequencies if we wish to we could slow + + align:start position:0% +frequencies if we wish to we could slow + + + align:start position:0% +frequencies if we wish to we could slow +the overall system we can certainly use + + align:start position:0% +the overall system we can certainly use + + + align:start position:0% +the overall system we can certainly use +larger than 20 pea farad capacitors uh + + align:start position:0% +larger than 20 pea farad capacitors uh + + + align:start position:0% +larger than 20 pea farad capacitors uh +that would result in in somewh improved + + align:start position:0% +that would result in in somewh improved + + + align:start position:0% +that would result in in somewh improved +stability although the stability of this + + align:start position:0% +stability although the stability of this + + + align:start position:0% +stability although the stability of this +one certainly looks good for many + + align:start position:0% +one certainly looks good for many + + + align:start position:0% +one certainly looks good for many +applications but would also generally + + align:start position:0% +applications but would also generally + + + align:start position:0% +applications but would also generally +slow the system and in fact the + + align:start position:0% +slow the system and in fact the + + + align:start position:0% +slow the system and in fact the +crossover of the major Loop would drop + + align:start position:0% +crossover of the major Loop would drop + + + align:start position:0% +crossover of the major Loop would drop +just about in proportion to that + + align:start position:0% +just about in proportion to that + + + align:start position:0% +just about in proportion to that +capacitor + + align:start position:0% +capacitor + + + align:start position:0% +capacitor +size now let's change the gain of the + + align:start position:0% +size now let's change the gain of the + + + align:start position:0% +size now let's change the gain of the +amplifier so that it's running at a at a + + align:start position:0% +amplifier so that it's running at a at a + + + align:start position:0% +amplifier so that it's running at a at a +closed loop gain of 10 rather than one + + align:start position:0% +closed loop gain of 10 rather than one + + + align:start position:0% +closed loop gain of 10 rather than one +in other words we'll change F by means + + align:start position:0% +in other words we'll change F by means + + + align:start position:0% +in other words we'll change F by means +of this switch to a tenth and when we do + + align:start position:0% +of this switch to a tenth and when we do + + + align:start position:0% +of this switch to a tenth and when we do +that we'll notice that the scope Trace + + align:start position:0% +that we'll notice that the scope Trace + + + align:start position:0% +that we'll notice that the scope Trace +gets considerably larger reflecting the + + align:start position:0% +gets considerably larger reflecting the + + + align:start position:0% +gets considerably larger reflecting the +factor of 10 increase in gain let me + + align:start position:0% +factor of 10 increase in gain let me + + + align:start position:0% +factor of 10 increase in gain let me +change the scale the vertical scale on + + align:start position:0% +change the scale the vertical scale on + + + align:start position:0% +change the scale the vertical scale on +the oscilloscope by again a factor of + + align:start position:0% +the oscilloscope by again a factor of + + + align:start position:0% +the oscilloscope by again a factor of +10 the important thing though for our + + align:start position:0% +10 the important thing though for our + + + align:start position:0% +10 the important thing though for our +purposes is that the step response has + + align:start position:0% +purposes is that the step response has + + + align:start position:0% +purposes is that the step response has +gotten much slower let's change the time + + align:start position:0% +gotten much slower let's change the time + + + align:start position:0% +gotten much slower let's change the time +scale and in fact here we are at one 1 + + align:start position:0% +scale and in fact here we are at one 1 + + + align:start position:0% +scale and in fact here we are at one 1 +microsc per division + + align:start position:0% +microsc per division + + + align:start position:0% +microsc per division +horizontally and + + align:start position:0% + + + + align:start position:0% + +and we can now measure the 10 to 90% + + align:start position:0% +and we can now measure the 10 to 90% + + + align:start position:0% +and we can now measure the 10 to 90% +rise + + align:start position:0% +rise + + + align:start position:0% +rise +time now between here and here we notice + + align:start position:0% +time now between here and here we notice + + + align:start position:0% +time now between here and here we notice +again it's very close to one and a half + + align:start position:0% +again it's very close to one and a half + + + align:start position:0% +again it's very close to one and a half +divisions uh this time we're at 1 + + align:start position:0% +divisions uh this time we're at 1 + + + align:start position:0% +divisions uh this time we're at 1 +microsc per division so we have a rise + + align:start position:0% +microsc per division so we have a rise + + + align:start position:0% +microsc per division so we have a rise +time with a 20 pea farad capacitor of 1 + + align:start position:0% +time with a 20 pea farad capacitor of 1 + + + align:start position:0% +time with a 20 pea farad capacitor of 1 +a half micros seconds when we have f a + + align:start position:0% +a half micros seconds when we have f a + + + align:start position:0% +a half micros seconds when we have f a +10th or 1 over F equal to + + align:start position:0% + + + + align:start position:0% + + + align:start position:0% + + + + align:start position:0% + +notice that the ratio is 10:1 which is + + align:start position:0% +notice that the ratio is 10:1 which is + + + align:start position:0% +notice that the ratio is 10:1 which is +exactly what we'd expect we found out + + align:start position:0% +exactly what we'd expect we found out + + + align:start position:0% +exactly what we'd expect we found out +that the time constant associated with + + align:start position:0% +that the time constant associated with + + + align:start position:0% +that the time constant associated with +the closed loop gain uh was proportional + + align:start position:0% +the closed loop gain uh was proportional + + + align:start position:0% +the closed loop gain uh was proportional +to the ratio C subc over F here we've + + align:start position:0% +to the ratio C subc over F here we've + + + align:start position:0% +to the ratio C subc over F here we've +kept C subc fixed we've changed F by a + + align:start position:0% +kept C subc fixed we've changed F by a + + + align:start position:0% +kept C subc fixed we've changed F by a +factor of a tenth we'd anticipate that + + align:start position:0% +factor of a tenth we'd anticipate that + + + align:start position:0% +factor of a tenth we'd anticipate that +the closed loop response would slow by + + align:start position:0% +the closed loop response would slow by + + + align:start position:0% +the closed loop response would slow by +just about that factor of 10 and in fact + + align:start position:0% +just about that factor of 10 and in fact + + + align:start position:0% +just about that factor of 10 and in fact +it does we also notice a little change + + align:start position:0% +it does we also notice a little change + + + align:start position:0% +it does we also notice a little change +in the character of the response uh the + + align:start position:0% +in the character of the response uh the + + + align:start position:0% +in the character of the response uh the +original response this one had just a + + align:start position:0% +original response this one had just a + + + align:start position:0% +original response this one had just a +little bit of + + align:start position:0% +little bit of + + + align:start position:0% +little bit of +overshoot once we uh are observing this + + align:start position:0% +overshoot once we uh are observing this + + + align:start position:0% +overshoot once we uh are observing this +response we noticed it looked very very + + align:start position:0% +response we noticed it looked very very + + + align:start position:0% +response we noticed it looked very very +much first + + align:start position:0% +much first + + + align:start position:0% +much first +order however we have lost the factor of + + align:start position:0% +order however we have lost the factor of + + + align:start position:0% +order however we have lost the factor of +10 in band in in response time or in + + align:start position:0% +10 in band in in response time or in + + + align:start position:0% +10 in band in in response time or in +bandwidth and we can buy that back by + + align:start position:0% +bandwidth and we can buy that back by + + + align:start position:0% +bandwidth and we can buy that back by +lowering the size of the capacitor by + + align:start position:0% +lowering the size of the capacitor by + + + align:start position:0% +lowering the size of the capacitor by +about a factor of 10 there's a a little + + align:start position:0% +about a factor of 10 there's a a little + + + align:start position:0% +about a factor of 10 there's a a little +bit of departure from the ideal case + + align:start position:0% +bit of departure from the ideal case + + + align:start position:0% +bit of departure from the ideal case +here there are a couple of uh effects in + + align:start position:0% +here there are a couple of uh effects in + + + align:start position:0% +here there are a couple of uh effects in +the amplifier that actually Force us to + + align:start position:0% +the amplifier that actually Force us to + + + align:start position:0% +the amplifier that actually Force us to +use a a capacitor that's somewhat larger + + align:start position:0% +use a a capacitor that's somewhat larger + + + align:start position:0% +use a a capacitor that's somewhat larger +than than on10th of of the previous + + align:start position:0% +than than on10th of of the previous + + + align:start position:0% +than than on10th of of the previous +value but we've made up a capacitor in + + align:start position:0% +value but we've made up a capacitor in + + + align:start position:0% +value but we've made up a capacitor in +that range uh made up a capacitor of + + align:start position:0% +that range uh made up a capacitor of + + + align:start position:0% +that range uh made up a capacitor of +about three Peak farads or + + align:start position:0% +about three Peak farads or + + + align:start position:0% +about three Peak farads or +thereabouts and we'll replace the + + align:start position:0% +thereabouts and we'll replace the + + + align:start position:0% +thereabouts and we'll replace the +compensating + + align:start position:0% +compensating + + + align:start position:0% +compensating +element with this lower value + + align:start position:0% +element with this lower value + + + align:start position:0% +element with this lower value +compensating + + align:start position:0% + + + + align:start position:0% + +capacitor and we find find out that we + + align:start position:0% +capacitor and we find find out that we + + + align:start position:0% +capacitor and we find find out that we +get a response that's very similar to + + align:start position:0% +get a response that's very similar to + + + align:start position:0% +get a response that's very similar to +the original one here we have just a a + + align:start position:0% +the original one here we have just a a + + + align:start position:0% +the original one here we have just a a +little bit of overshoot so we're back to + + align:start position:0% +little bit of overshoot so we're back to + + + align:start position:0% +little bit of overshoot so we're back to +corresponding to stability actually + + align:start position:0% +corresponding to stability actually + + + align:start position:0% +corresponding to stability actually +probably a little bit better than the + + align:start position:0% +probably a little bit better than the + + + align:start position:0% +probably a little bit better than the +original one this this capacitor might + + align:start position:0% +original one this this capacitor might + + + align:start position:0% +original one this this capacitor might +be a little larger uh than the one that + + align:start position:0% +be a little larger uh than the one that + + + align:start position:0% +be a little larger uh than the one that +would give us exactly the same amount of + + align:start position:0% +would give us exactly the same amount of + + + align:start position:0% +would give us exactly the same amount of +of overshoot as we got in the first + + align:start position:0% +of overshoot as we got in the first + + + align:start position:0% +of overshoot as we got in the first +experiment we can measure the 10 to 90% + + align:start position:0% +experiment we can measure the 10 to 90% + + + align:start position:0% +experiment we can measure the 10 to 90% +rise time in this + + align:start position:0% + + + + align:start position:0% + +case uh and and let's see let me go back + + align:start position:0% +case uh and and let's see let me go back + + + align:start position:0% +case uh and and let's see let me go back +to 100 nond per + + align:start position:0% + + + + align:start position:0% + +division uh here's 10% 90% Let's see we + + align:start position:0% +division uh here's 10% 90% Let's see we + + + align:start position:0% +division uh here's 10% 90% Let's see we +have one two about two and a half + + align:start position:0% +have one two about two and a half + + + align:start position:0% +have one two about two and a half +divisions and + + align:start position:0% +divisions and + + + align:start position:0% +divisions and +so we're able to by choosing an + + align:start position:0% +so we're able to by choosing an + + + align:start position:0% +so we're able to by choosing an +appropriate capacitor reduce the rise + + align:start position:0% +appropriate capacitor reduce the rise + + + align:start position:0% +appropriate capacitor reduce the rise +time not quite to its original value but + + align:start position:0% +time not quite to its original value but + + + align:start position:0% +time not quite to its original value but +we get about + + align:start position:0% +we get about + + + align:start position:0% +we get about +250 Nan so rather than losing a factor + + align:start position:0% +250 Nan so rather than losing a factor + + + align:start position:0% +250 Nan so rather than losing a factor +of 10:1 in bandwidth or rise time we've + + align:start position:0% +of 10:1 in bandwidth or rise time we've + + + align:start position:0% +of 10:1 in bandwidth or rise time we've +lost a factor of of maybe + + align:start position:0% +lost a factor of of maybe + + + align:start position:0% +lost a factor of of maybe +6:1 well let's + + align:start position:0% +6:1 well let's + + + align:start position:0% +6:1 well let's +continue let's first of all go back to + + align:start position:0% +continue let's first of all go back to + + + align:start position:0% +continue let's first of all go back to +the original 20 paa + + align:start position:0% +the original 20 paa + + + align:start position:0% +the original 20 paa +farad + + align:start position:0% + + + + align:start position:0% + +capacitor and now up the gain by another + + align:start position:0% +capacitor and now up the gain by another + + + align:start position:0% +capacitor and now up the gain by another +factor of 10 if I throw this switch down + + align:start position:0% +factor of 10 if I throw this switch down + + + align:start position:0% +factor of 10 if I throw this switch down +we get a a closed loop gain of 100 we + + align:start position:0% +we get a a closed loop gain of 100 we + + + align:start position:0% +we get a a closed loop gain of 100 we +make f + + align:start position:0% +make f + + + align:start position:0% +make f +1/100th let me do that and again I have + + align:start position:0% +1/100th let me do that and again I have + + + align:start position:0% +1/100th let me do that and again I have +to change the vertical scale on the + + align:start position:0% + + + + align:start position:0% + +oscilloscope we find out now the the + + align:start position:0% +oscilloscope we find out now the the + + + align:start position:0% +oscilloscope we find out now the the +bandwidth is so deteriorated with the + + align:start position:0% +bandwidth is so deteriorated with the + + + align:start position:0% +bandwidth is so deteriorated with the +original value for the capacitor that we + + align:start position:0% +original value for the capacitor that we + + + align:start position:0% +original value for the capacitor that we +have to slow the signal generator so let + + align:start position:0% +have to slow the signal generator so let + + + align:start position:0% +have to slow the signal generator so let +me do that so that we reach final + + align:start position:0% +me do that so that we reach final + + + align:start position:0% +me do that so that we reach final +value all right and here is the step + + align:start position:0% +value all right and here is the step + + + align:start position:0% +value all right and here is the step +response that corresponds to a 20 peaka + + align:start position:0% +response that corresponds to a 20 peaka + + + align:start position:0% +response that corresponds to a 20 peaka +farad capacitor and a closed loop gain + + align:start position:0% +farad capacitor and a closed loop gain + + + align:start position:0% +farad capacitor and a closed loop gain +of 100 + + align:start position:0% +of 100 + + + align:start position:0% +of 100 +uh the amplitude is down just a little + + align:start position:0% +uh the amplitude is down just a little + + + align:start position:0% +uh the amplitude is down just a little +bit let me increase that so that we can + + align:start position:0% +bit let me increase that so that we can + + + align:start position:0% +bit let me increase that so that we can +easily measure the 10 to 90% rise + + align:start position:0% +easily measure the 10 to 90% rise + + + align:start position:0% +easily measure the 10 to 90% rise +time we notice the response is very much + + align:start position:0% +time we notice the response is very much + + + align:start position:0% +time we notice the response is very much +first order uh here we're at five + + align:start position:0% +first order uh here we're at five + + + align:start position:0% +first order uh here we're at five +microsc per division uh one two just a + + align:start position:0% +microsc per division uh one two just a + + + align:start position:0% +microsc per division uh one two just a +little bit more than three divisions so + + align:start position:0% +little bit more than three divisions so + + + align:start position:0% +little bit more than three divisions so +we have a 10 to 90% rise time of just + + align:start position:0% +we have a 10 to 90% rise time of just + + + align:start position:0% +we have a 10 to 90% rise time of just +about 15 micros seconds again we're + + align:start position:0% +about 15 micros seconds again we're + + + align:start position:0% +about 15 micros seconds again we're +since we're + + align:start position:0% +since we're + + + align:start position:0% +since we're +comparing in this column uh the response + + align:start position:0% +comparing in this column uh the response + + + align:start position:0% +comparing in this column uh the response +that we get with an equal value for C + + align:start position:0% +that we get with an equal value for C + + + align:start position:0% +that we get with an equal value for C +subc but progressively smaller values of + + align:start position:0% +subc but progressively smaller values of + + + align:start position:0% +subc but progressively smaller values of +f we'd anticipate that this value would + + align:start position:0% +f we'd anticipate that this value would + + + align:start position:0% +f we'd anticipate that this value would +simply go as 1 over F and we see that + + align:start position:0% +simply go as 1 over F and we see that + + + align:start position:0% +simply go as 1 over F and we see that +that's that's what + + align:start position:0% +that's that's what + + + align:start position:0% +that's that's what +happens again we can get close to our + + align:start position:0% +happens again we can get close to our + + + align:start position:0% +happens again we can get close to our +original speed of response by removing + + align:start position:0% +original speed of response by removing + + + align:start position:0% +original speed of response by removing +the 20 pea farad + + align:start position:0% +the 20 pea farad + + + align:start position:0% +the 20 pea farad +capacitor and replacing it with one + + align:start position:0% +capacitor and replacing it with one + + + align:start position:0% +capacitor and replacing it with one +that has been chosen to say it's not + + align:start position:0% +that has been chosen to say it's not + + + align:start position:0% +that has been chosen to say it's not +quite 1/ 100th of the original value but + + align:start position:0% +quite 1/ 100th of the original value but + + + align:start position:0% +quite 1/ 100th of the original value but +one that's been + + align:start position:0% +one that's been + + + align:start position:0% +one that's been +chosen to yield very close to the + + align:start position:0% +chosen to yield very close to the + + + align:start position:0% +chosen to yield very close to the +original + + align:start position:0% +original + + + align:start position:0% +original +Dynamics and we get that sort of a + + align:start position:0% +Dynamics and we get that sort of a + + + align:start position:0% +Dynamics and we get that sort of a +response much faster notice very nearly + + align:start position:0% +response much faster notice very nearly + + + align:start position:0% +response much faster notice very nearly +vertical rise on this kind of a time + + align:start position:0% +vertical rise on this kind of a time + + + align:start position:0% +vertical rise on this kind of a time +scale uh we can now speed up the + + align:start position:0% +scale uh we can now speed up the + + + align:start position:0% +scale uh we can now speed up the +generator once + + align:start position:0% +generator once + + + align:start position:0% +generator once +again look at the response in + + align:start position:0% +again look at the response in + + + align:start position:0% +again look at the response in +detail and again our 10 to 90 % rise + + align:start position:0% +detail and again our 10 to 90 % rise + + + align:start position:0% +detail and again our 10 to 90 % rise +time we're now back to a time scale of + + align:start position:0% +time we're now back to a time scale of + + + align:start position:0% +time we're now back to a time scale of +200 nond per division uh the 10 to 90% + + align:start position:0% +200 nond per division uh the 10 to 90% + + + align:start position:0% +200 nond per division uh the 10 to 90% +rise time is back to about 500 + + align:start position:0% +rise time is back to about 500 + + + align:start position:0% +rise time is back to about 500 +NCS one two two and a half divisions uh + + align:start position:0% +NCS one two two and a half divisions uh + + + align:start position:0% +NCS one two two and a half divisions uh +at 200 nond per + + align:start position:0% +at 200 nond per + + + align:start position:0% +at 200 nond per +division so again we haven't quite + + align:start position:0% +division so again we haven't quite + + + align:start position:0% +division so again we haven't quite +gotten back to the original + + align:start position:0% + + + + align:start position:0% + +case but we're roughly a factor of 30 + + align:start position:0% +case but we're roughly a factor of 30 + + + align:start position:0% +case but we're roughly a factor of 30 +faster than uh the case that that + + align:start position:0% +faster than uh the case that that + + + align:start position:0% +faster than uh the case that that +resulted when we use the capacitor that + + align:start position:0% +resulted when we use the capacitor that + + + align:start position:0% +resulted when we use the capacitor that +was selected for Unity gain stability or + + align:start position:0% +was selected for Unity gain stability or + + + align:start position:0% +was selected for Unity gain stability or +for Unity feedback so we've made a very + + align:start position:0% +for Unity feedback so we've made a very + + + align:start position:0% +for Unity feedback so we've made a very +very dramatic Improvement in the + + align:start position:0% +very dramatic Improvement in the + + + align:start position:0% +very dramatic Improvement in the +bandwidth of the amplifier by simply + + align:start position:0% +bandwidth of the amplifier by simply + + + align:start position:0% +bandwidth of the amplifier by simply +choosing the compensating capacitor as a + + align:start position:0% +choosing the compensating capacitor as a + + + align:start position:0% +choosing the compensating capacitor as a +function of the closed loop + + align:start position:0% +function of the closed loop + + + align:start position:0% +function of the closed loop +gain finally let me go back to the + + align:start position:0% +gain finally let me go back to the + + + align:start position:0% +gain finally let me go back to the +original value the 20 paaf farad + + align:start position:0% +original value the 20 paaf farad + + + align:start position:0% +original value the 20 paaf farad +compensating capacitor one last + + align:start position:0% + + + + align:start position:0% + +time and now let's increase the closed + + align:start position:0% +time and now let's increase the closed + + + align:start position:0% +time and now let's increase the closed +loop gain to a + + align:start position:0% + + + + align:start position:0% + +th000 uh we clearly are going very very + + align:start position:0% +th000 uh we clearly are going very very + + + align:start position:0% +th000 uh we clearly are going very very +slowly let's slow down the generator uh + + align:start position:0% +slowly let's slow down the generator uh + + + align:start position:0% +slowly let's slow down the generator uh +things saturate we've got to put in a + + align:start position:0% +things saturate we've got to put in a + + + align:start position:0% +things saturate we've got to put in a +smaller + + align:start position:0% +smaller + + + align:start position:0% +smaller +signal uh we still haven't reached final + + align:start position:0% +signal uh we still haven't reached final + + + align:start position:0% +signal uh we still haven't reached final +value all + + align:start position:0% +value all + + + align:start position:0% +value all +right now we finally have things + + align:start position:0% +right now we finally have things + + + align:start position:0% +right now we finally have things +adjusted so that we can see the rise + + align:start position:0% +adjusted so that we can see the rise + + + align:start position:0% +adjusted so that we can see the rise +time with the 20 peaka farad capacitor + + align:start position:0% +time with the 20 peaka farad capacitor + + + align:start position:0% +time with the 20 peaka farad capacitor +at a closed loop gain of a + + align:start position:0% +at a closed loop gain of a + + + align:start position:0% +at a closed loop gain of a +th000 and if we make the rise time + + align:start position:0% +th000 and if we make the rise time + + + align:start position:0% +th000 and if we make the rise time +measurement this time let's see we're at + + align:start position:0% +measurement this time let's see we're at + + + align:start position:0% +measurement this time let's see we're at +50 micros seconds per division uh so we + + align:start position:0% +50 micros seconds per division uh so we + + + align:start position:0% +50 micros seconds per division uh so we +have one two again just about three + + align:start position:0% +have one two again just about three + + + align:start position:0% +have one two again just about three +divisions for the rise time uh so we + + align:start position:0% +divisions for the rise time uh so we + + + align:start position:0% +divisions for the rise time uh so we +have a rise time of about 150 micros + + align:start position:0% +have a rise time of about 150 micros + + + align:start position:0% +have a rise time of about 150 micros +seconds our amplifier as we anticipated + + align:start position:0% +seconds our amplifier as we anticipated + + + align:start position:0% +seconds our amplifier as we anticipated +has gotten a + + align:start position:0% +has gotten a + + + align:start position:0% +has gotten a +factor of a thousand slower than the + + align:start position:0% +factor of a thousand slower than the + + + align:start position:0% +factor of a thousand slower than the +original + + align:start position:0% +original + + + align:start position:0% +original +case if we interpret this in in + + align:start position:0% +case if we interpret this in in + + + align:start position:0% +case if we interpret this in in +bandwidth in terms of bandwidth rather + + align:start position:0% +bandwidth in terms of bandwidth rather + + + align:start position:0% +bandwidth in terms of bandwidth rather +than rise time here we had a bandwidth + + align:start position:0% +than rise time here we had a bandwidth + + + align:start position:0% +than rise time here we had a bandwidth +of very nearly 2 MHz or actually a + + align:start position:0% +of very nearly 2 MHz or actually a + + + align:start position:0% +of very nearly 2 MHz or actually a +little bit more remember the product of + + align:start position:0% +little bit more remember the product of + + + align:start position:0% +little bit more remember the product of +Rise time times bandwidth in hertz is + + align:start position:0% +Rise time times bandwidth in hertz is + + + align:start position:0% +Rise time times bandwidth in hertz is +about. 35 so this corresponds to + + align:start position:0% +about. 35 so this corresponds to + + + align:start position:0% +about. 35 so this corresponds to +something like 2.3 megahertz of closed + + align:start position:0% +something like 2.3 megahertz of closed + + + align:start position:0% +something like 2.3 megahertz of closed +loop + + align:start position:0% +loop + + + align:start position:0% +loop +bandwidth this corresponds to a factor + + align:start position:0% +bandwidth this corresponds to a factor + + + align:start position:0% +bandwidth this corresponds to a factor +of a th000 smaller than that + + align:start position:0% +of a th000 smaller than that + + + align:start position:0% +of a th000 smaller than that +approximately 2 khz so here at a closed + + align:start position:0% +approximately 2 khz so here at a closed + + + align:start position:0% +approximately 2 khz so here at a closed +loop gain of a th000 we're not even able + + align:start position:0% +loop gain of a th000 we're not even able + + + align:start position:0% +loop gain of a th000 we're not even able +to accomplish + + align:start position:0% +to accomplish + + + align:start position:0% +to accomplish +to to get significantly through the + + align:start position:0% +to to get significantly through the + + + align:start position:0% +to to get significantly through the +audio band The bandwidth of the + + align:start position:0% +audio band The bandwidth of the + + + align:start position:0% +audio band The bandwidth of the +amplifier is about 2 khz if we had used + + align:start position:0% +amplifier is about 2 khz if we had used + + + align:start position:0% +amplifier is about 2 khz if we had used +a 741 which uses fixed compensation for + + align:start position:0% +a 741 which uses fixed compensation for + + + align:start position:0% +a 741 which uses fixed compensation for +all of these experiments uh its numbers + + align:start position:0% +all of these experiments uh its numbers + + + align:start position:0% +all of these experiments uh its numbers +are such that we'd actually have about a + + align:start position:0% +are such that we'd actually have about a + + + align:start position:0% +are such that we'd actually have about a +kilohertz of bandwidth under these + + align:start position:0% +kilohertz of bandwidth under these + + + align:start position:0% +kilohertz of bandwidth under these +conditions well let's see what we can do + + align:start position:0% +conditions well let's see what we can do + + + align:start position:0% +conditions well let's see what we can do +if we compensate the amplifier properly + + align:start position:0% +if we compensate the amplifier properly + + + align:start position:0% +if we compensate the amplifier properly +instead of using the fixed + + align:start position:0% +instead of using the fixed + + + align:start position:0% +instead of using the fixed +compensation uh let me remove the + + align:start position:0% +compensation uh let me remove the + + + align:start position:0% +compensation uh let me remove the +compensation entirely when we do that + + align:start position:0% +compensation entirely when we do that + + + align:start position:0% +compensation entirely when we do that +our approximation begins to break break + + align:start position:0% +our approximation begins to break break + + + align:start position:0% +our approximation begins to break break +down a little bit but we find out that + + align:start position:0% +down a little bit but we find out that + + + align:start position:0% +down a little bit but we find out that +even we can now speed up things + + align:start position:0% + + + + align:start position:0% + +uh even with this large a value of f in + + align:start position:0% +uh even with this large a value of f in + + + align:start position:0% +uh even with this large a value of f in +the feedback path or the small a value + + align:start position:0% +the feedback path or the small a value + + + align:start position:0% +the feedback path or the small a value +of F this much attenuation in the + + align:start position:0% +of F this much attenuation in the + + + align:start position:0% +of F this much attenuation in the +feedback path the amplifier is actually + + align:start position:0% +feedback path the amplifier is actually + + + align:start position:0% +feedback path the amplifier is actually +still underdamped we notice considerable + + align:start position:0% +still underdamped we notice considerable + + + align:start position:0% +still underdamped we notice considerable +overshoot to the step response with no + + align:start position:0% +overshoot to the step response with no + + + align:start position:0% +overshoot to the step response with no +comp compens ation we we see there might + + align:start position:0% +comp compens ation we we see there might + + + align:start position:0% +comp compens ation we we see there might +be something like 30% overshoot or 40% + + align:start position:0% +be something like 30% overshoot or 40% + + + align:start position:0% +be something like 30% overshoot or 40% +overshoot uh reasonably high frequency + + align:start position:0% +overshoot uh reasonably high frequency + + + align:start position:0% +overshoot uh reasonably high frequency +ring ringing at at about 300 kohtz we + + align:start position:0% +ring ringing at at about 300 kohtz we + + + align:start position:0% +ring ringing at at about 300 kohtz we +have one microsc per division + + align:start position:0% +have one microsc per division + + + align:start position:0% +have one microsc per division +horizontally now so let's see if we can + + align:start position:0% +horizontally now so let's see if we can + + + align:start position:0% +horizontally now so let's see if we can +compensate that if we uh really believed + + align:start position:0% +compensate that if we uh really believed + + + align:start position:0% +compensate that if we uh really believed +our numbers we'd conclude that we needed + + align:start position:0% +our numbers we'd conclude that we needed + + + align:start position:0% +our numbers we'd conclude that we needed +20 paa farads divided by a th000 and + + align:start position:0% +20 paa farads divided by a th000 and + + + align:start position:0% +20 paa farads divided by a th000 and +that seems somewhat unrealistic actually + + align:start position:0% +that seems somewhat unrealistic actually + + + align:start position:0% +that seems somewhat unrealistic actually +we need a capacitor a little bit larger + + align:start position:0% +we need a capacitor a little bit larger + + + align:start position:0% +we need a capacitor a little bit larger +than that but let's get our capacitor + + align:start position:0% +than that but let's get our capacitor + + + align:start position:0% +than that but let's get our capacitor +this way I simply have two pieces of + + align:start position:0% +this way I simply have two pieces of + + + align:start position:0% +this way I simply have two pieces of +wire that I'll put into the compensating + + align:start position:0% + + + + align:start position:0% + +Terminals and we now have a very + + align:start position:0% +Terminals and we now have a very + + + align:start position:0% +Terminals and we now have a very +convenient method for adjusting + + align:start position:0% +convenient method for adjusting + + + align:start position:0% +convenient method for adjusting +capacitance at very small values uh if + + align:start position:0% +capacitance at very small values uh if + + + align:start position:0% +capacitance at very small values uh if +we get these + + align:start position:0% +we get these + + + align:start position:0% +we get these +apart we have the undercompensated case + + align:start position:0% +apart we have the undercompensated case + + + align:start position:0% +apart we have the undercompensated case +with a reasonable amount of overshoot as + + align:start position:0% +with a reasonable amount of overshoot as + + + align:start position:0% +with a reasonable amount of overshoot as +we move the two wires + + align:start position:0% +we move the two wires + + + align:start position:0% +we move the two wires +together + + align:start position:0% +together + + + align:start position:0% +together +we're able to get progressively better + + align:start position:0% +we're able to get progressively better + + + align:start position:0% +we're able to get progressively better +damping here's a critically damp case no + + align:start position:0% +damping here's a critically damp case no + + + align:start position:0% +damping here's a critically damp case no +overshoot the closed loop holes are + + align:start position:0% +overshoot the closed loop holes are + + + align:start position:0% +overshoot the closed loop holes are +appear to all be on the real axis and + + align:start position:0% +appear to all be on the real axis and + + + align:start position:0% +appear to all be on the real axis and +let's see if we can get back to pretty + + align:start position:0% +let's see if we can get back to pretty + + + align:start position:0% +let's see if we can get back to pretty +close to the original + + align:start position:0% +close to the original + + + align:start position:0% +close to the original +situation something like that so in this + + align:start position:0% +situation something like that so in this + + + align:start position:0% +situation something like that so in this +way by adjusting the capacitance we're + + align:start position:0% +way by adjusting the capacitance we're + + + align:start position:0% +way by adjusting the capacitance we're +able to very well control the Dynamics + + align:start position:0% +able to very well control the Dynamics + + + align:start position:0% +able to very well control the Dynamics +the transient response also we get back + + align:start position:0% +the transient response also we get back + + + align:start position:0% +the transient response also we get back +to a very + + align:start position:0% +to a very + + + align:start position:0% +to a very +respectable value for Rise time here + + align:start position:0% +respectable value for Rise time here + + + align:start position:0% +respectable value for Rise time here +we're at 500 NCS per + + align:start position:0% +we're at 500 NCS per + + + align:start position:0% +we're at 500 NCS per +division uh if we measure the 10 to 90% + + align:start position:0% +division uh if we measure the 10 to 90% + + + align:start position:0% +division uh if we measure the 10 to 90% +rise time we find out it's just about + + align:start position:0% +rise time we find out it's just about + + + align:start position:0% +rise time we find out it's just about +two divisions on that time scale from + + align:start position:0% +two divisions on that time scale from + + + align:start position:0% +two divisions on that time scale from +here to + + align:start position:0% +here to + + + align:start position:0% +here to +here so uh we get about a one micr + + align:start position:0% +here so uh we get about a one micr + + + align:start position:0% +here so uh we get about a one micr +second Rise time roughly a factor of 150 + + align:start position:0% +second Rise time roughly a factor of 150 + + + align:start position:0% +second Rise time roughly a factor of 150 +to one Improvement in rise time and + + align:start position:0% +to one Improvement in rise time and + + + align:start position:0% +to one Improvement in rise time and +correspondingly bandwidth when we + + align:start position:0% +correspondingly bandwidth when we + + + align:start position:0% +correspondingly bandwidth when we +compensate with this small value of + + align:start position:0% +compensate with this small value of + + + align:start position:0% +compensate with this small value of +capacitor we still have something like a + + align:start position:0% +capacitor we still have something like a + + + align:start position:0% +capacitor we still have something like a +350 khz closed loop bandwidth at a gain + + align:start position:0% +350 khz closed loop bandwidth at a gain + + + align:start position:0% +350 khz closed loop bandwidth at a gain +of a + + align:start position:0% + + + + align:start position:0% + +th000 we might question the practicality + + align:start position:0% +th000 we might question the practicality + + + align:start position:0% +th000 we might question the practicality +of all of this when in fact in order to + + align:start position:0% +of all of this when in fact in order to + + + align:start position:0% +of all of this when in fact in order to +compensate we have to do something like + + align:start position:0% +compensate we have to do something like + + + align:start position:0% +compensate we have to do something like +this and wave two two components two + + align:start position:0% +this and wave two two components two + + + align:start position:0% +this and wave two two components two +wands at each other but in reality we + + align:start position:0% +wands at each other but in reality we + + + align:start position:0% +wands at each other but in reality we +find out we can do that fairly well if + + align:start position:0% +find out we can do that fairly well if + + + align:start position:0% +find out we can do that fairly well if +we back off just a little bit from sort + + align:start position:0% +we back off just a little bit from sort + + + align:start position:0% +we back off just a little bit from sort +of the optimum situation and and + + align:start position:0% +of the optimum situation and and + + + align:start position:0% +of the optimum situation and and +conclude that we're going to + + align:start position:0% +conclude that we're going to + + + align:start position:0% +conclude that we're going to +overcompensate a little bit maybe only + + align:start position:0% +overcompensate a little bit maybe only + + + align:start position:0% +overcompensate a little bit maybe only +get 100 or or 150 khz of bandwidth + + align:start position:0% +get 100 or or 150 khz of bandwidth + + + align:start position:0% +get 100 or or 150 khz of bandwidth +instead of trying to stretch things out + + align:start position:0% +instead of trying to stretch things out + + + align:start position:0% +instead of trying to stretch things out +and get 350 khz we can do that quite + + align:start position:0% +and get 350 khz we can do that quite + + + align:start position:0% +and get 350 khz we can do that quite +repeatedly furthermore there are + + align:start position:0% +repeatedly furthermore there are + + + align:start position:0% +repeatedly furthermore there are +techniques which certainly have been + + align:start position:0% +techniques which certainly have been + + + align:start position:0% +techniques which certainly have been +used uh for example you can lay out a + + align:start position:0% +used uh for example you can lay out a + + + align:start position:0% +used uh for example you can lay out a +printed circuit board and and peel back + + align:start position:0% +printed circuit board and and peel back + + + align:start position:0% +printed circuit board and and peel back +foil or something to make the adjustment + + align:start position:0% +foil or something to make the adjustment + + + align:start position:0% +foil or something to make the adjustment +to tailor particular circuit values to a + + align:start position:0% +to tailor particular circuit values to a + + + align:start position:0% +to tailor particular circuit values to a +specific operational amplifier but it's + + align:start position:0% +specific operational amplifier but it's + + + align:start position:0% +specific operational amplifier but it's +say if you're a little bit concerned + + align:start position:0% +say if you're a little bit concerned + + + align:start position:0% +say if you're a little bit concerned +about that why you can certainly get + + align:start position:0% +about that why you can certainly get + + + align:start position:0% +about that why you can certainly get +most of the benefits be a little bit + + align:start position:0% +most of the benefits be a little bit + + + align:start position:0% +most of the benefits be a little bit +more conservative by by simply + + align:start position:0% +more conservative by by simply + + + align:start position:0% +more conservative by by simply +overcompensating a little bit and ending + + align:start position:0% +overcompensating a little bit and ending + + + align:start position:0% +overcompensating a little bit and ending +up with still far far better Dynamics + + align:start position:0% +up with still far far better Dynamics + + + align:start position:0% +up with still far far better Dynamics +than those that result if you use a + + align:start position:0% +than those that result if you use a + + + align:start position:0% +than those that result if you use a +fixed compensating + + align:start position:0% +fixed compensating + + + align:start position:0% +fixed compensating +element well single pole compensation is + + align:start position:0% +element well single pole compensation is + + + align:start position:0% +element well single pole compensation is +a very good general purpose kind of + + align:start position:0% +a very good general purpose kind of + + + align:start position:0% +a very good general purpose kind of +compensation uh it's the one that's + + align:start position:0% +compensation uh it's the one that's + + + align:start position:0% +compensation uh it's the one that's +normally used when when fixed comp + + align:start position:0% +normally used when when fixed comp + + + align:start position:0% +normally used when when fixed comp +compensation amplifiers are sold it say + + align:start position:0% +compensation amplifiers are sold it say + + + align:start position:0% +compensation amplifiers are sold it say +it it can be certainly designed so that + + align:start position:0% +it it can be certainly designed so that + + + align:start position:0% +it it can be certainly designed so that +the amplifier is stable in a variety of + + align:start position:0% +the amplifier is stable in a variety of + + + align:start position:0% +the amplifier is stable in a variety of +feedback connections it's only or one of + + align:start position:0% +feedback connections it's only or one of + + + align:start position:0% +feedback connections it's only or one of +its problems is simply that it's overly + + align:start position:0% +its problems is simply that it's overly + + + align:start position:0% +its problems is simply that it's overly +conservative in many applications as + + align:start position:0% +conservative in many applications as + + + align:start position:0% +conservative in many applications as +we've + + align:start position:0% +we've + + + align:start position:0% +we've +seen another + + align:start position:0% +seen another + + + align:start position:0% +seen another +possibility uh is to consider the + + align:start position:0% +possibility uh is to consider the + + + align:start position:0% +possibility uh is to consider the +following let's + + align:start position:0% +following let's + + + align:start position:0% +following let's +suppose that + + align:start position:0% +suppose that + + + align:start position:0% +suppose that +this is + + align:start position:0% +this is + + + align:start position:0% +this is +the open loop transfer function of the + + align:start position:0% +the open loop transfer function of the + + + align:start position:0% +the open loop transfer function of the +amplifier without compensation when we + + align:start position:0% +amplifier without compensation when we + + + align:start position:0% +amplifier without compensation when we +consider the effects of loading by the + + align:start position:0% +consider the effects of loading by the + + + align:start position:0% +consider the effects of loading by the +compensating Network in in general why + + align:start position:0% +compensating Network in in general why + + + align:start position:0% +compensating Network in in general why +the the compensating network doesn't the + + align:start position:0% +the the compensating network doesn't the + + + align:start position:0% +the the compensating network doesn't the +loading of the compensating Network + + align:start position:0% +loading of the compensating Network + + + align:start position:0% +loading of the compensating Network +usually doesn't change that curve much + + align:start position:0% +usually doesn't change that curve much + + + align:start position:0% +usually doesn't change that curve much +so let's suppose somehow we know that + + align:start position:0% +so let's suppose somehow we know that + + + align:start position:0% +so let's suppose somehow we know that +this is + + align:start position:0% +this is + + + align:start position:0% +this is +the uncompensated open loop transfer + + align:start position:0% +the uncompensated open loop transfer + + + align:start position:0% +the uncompensated open loop transfer +function for the amplifier if we use + + align:start position:0% +function for the amplifier if we use + + + align:start position:0% +function for the amplifier if we use +single pole compensation and possibly + + align:start position:0% +single pole compensation and possibly + + + align:start position:0% +single pole compensation and possibly +adjust it for Unity gain at a megahertz + + align:start position:0% +adjust it for Unity gain at a megahertz + + + align:start position:0% +adjust it for Unity gain at a megahertz +or something like that why this is the + + align:start position:0% +or something like that why this is the + + + align:start position:0% +or something like that why this is the +approximating function our + + align:start position:0% +approximating function our + + + align:start position:0% +approximating function our +approximation tells us that at least + + align:start position:0% +approximation tells us that at least + + + align:start position:0% +approximation tells us that at least +over from here to this frequency and and + + align:start position:0% +over from here to this frequency and and + + + align:start position:0% +over from here to this frequency and and +possibly Beyond we'll have basically a + + align:start position:0% +possibly Beyond we'll have basically a + + + align:start position:0% +possibly Beyond we'll have basically a +single pole rollof associated with the + + align:start position:0% +single pole rollof associated with the + + + align:start position:0% +single pole rollof associated with the +open loop transfer function of the + + align:start position:0% +open loop transfer function of the + + + align:start position:0% +open loop transfer function of the +amplifier uh we might wonder though + + align:start position:0% +amplifier uh we might wonder though + + + align:start position:0% +amplifier uh we might wonder though +we're throwing away a good bit of + + align:start position:0% +we're throwing away a good bit of + + + align:start position:0% +we're throwing away a good bit of +amplifier capability this area here + + align:start position:0% +amplifier capability this area here + + + align:start position:0% +amplifier capability this area here +represents a region where the amplifier + + align:start position:0% +represents a region where the amplifier + + + align:start position:0% +represents a region where the amplifier +has considerably more open loop gain + + align:start position:0% +has considerably more open loop gain + + + align:start position:0% +has considerably more open loop gain +potential than we're actually using + + align:start position:0% +potential than we're actually using + + + align:start position:0% +potential than we're actually using +we've had a squeeze sze down the open + + align:start position:0% +we've had a squeeze sze down the open + + + align:start position:0% +we've had a squeeze sze down the open +loop gain over a very wide range of + + align:start position:0% +loop gain over a very wide range of + + + align:start position:0% +loop gain over a very wide range of +frequencies in order to make the + + align:start position:0% +frequencies in order to make the + + + align:start position:0% +frequencies in order to make the +amplifier + + align:start position:0% +amplifier + + + align:start position:0% +amplifier +stable well what would happen if we used + + align:start position:0% +stable well what would happen if we used + + + align:start position:0% +stable well what would happen if we used +a somewhat different kind of roll off a + + align:start position:0% +a somewhat different kind of roll off a + + + align:start position:0% +a somewhat different kind of roll off a +somewhat more heroic roll off if you + + align:start position:0% +somewhat more heroic roll off if you + + + align:start position:0% +somewhat more heroic roll off if you +will uh let's keep a single pole roll + + align:start position:0% +will uh let's keep a single pole roll + + + align:start position:0% +will uh let's keep a single pole roll +off in the vicinity of crossover let's + + align:start position:0% +off in the vicinity of crossover let's + + + align:start position:0% +off in the vicinity of crossover let's +assume this is a plot of the AF product + + align:start position:0% +assume this is a plot of the AF product + + + align:start position:0% +assume this is a plot of the AF product +so it includes F let's keep a single + + align:start position:0% +so it includes F let's keep a single + + + align:start position:0% +so it includes F let's keep a single +pole roll off in the vicinity of + + align:start position:0% +pole roll off in the vicinity of + + + align:start position:0% +pole roll off in the vicinity of +crossover but let's roll off as 1 / s + + align:start position:0% +crossover but let's roll off as 1 / s + + + align:start position:0% +crossover but let's roll off as 1 / s +squ at lower + + align:start position:0% + + + + align:start position:0% + +frequencies maybe something like so our + + align:start position:0% +frequencies maybe something like so our + + + align:start position:0% +frequencies maybe something like so our +approximation now becomes one/ s squ or + + align:start position:0% +approximation now becomes one/ s squ or + + + align:start position:0% +approximation now becomes one/ s squ or +some constant over s s and then a single + + align:start position:0% +some constant over s s and then a single + + + align:start position:0% +some constant over s s and then a single +pole roll off uh the actual open loop + + align:start position:0% +pole roll off uh the actual open loop + + + align:start position:0% +pole roll off uh the actual open loop +transfer function of the amplifier again + + align:start position:0% +transfer function of the amplifier again + + + align:start position:0% +transfer function of the amplifier again +would be the lower of these two curves + + align:start position:0% +would be the lower of these two curves + + + align:start position:0% +would be the lower of these two curves +at all frequencies so it might look + + align:start position:0% +at all frequencies so it might look + + + align:start position:0% +at all frequencies so it might look +something like that but the important + + align:start position:0% +something like that but the important + + + align:start position:0% +something like that but the important +point is that we've picked up a good bit + + align:start position:0% +point is that we've picked up a good bit + + + align:start position:0% +point is that we've picked up a good bit +of area in here we've increased + + align:start position:0% +of area in here we've increased + + + align:start position:0% +of area in here we've increased +desensitivity over a very wide range of + + align:start position:0% +desensitivity over a very wide range of + + + align:start position:0% +desensitivity over a very wide range of +frequencies by using two- pole + + align:start position:0% +frequencies by using two- pole + + + align:start position:0% +frequencies by using two- pole +compensation as opposed to one pole + + align:start position:0% +compensation as opposed to one pole + + + align:start position:0% +compensation as opposed to one pole +compensation in order to implement two- + + align:start position:0% +compensation in order to implement two- + + + align:start position:0% +compensation in order to implement two- +pole compensation we want to make the + + align:start position:0% +pole compensation we want to make the + + + align:start position:0% +pole compensation we want to make the +ratio G subm over 2 y Sub C of s have + + align:start position:0% +ratio G subm over 2 y Sub C of s have + + + align:start position:0% +ratio G subm over 2 y Sub C of s have +the general form K to S + 1/ s^ 2 the k/ + + align:start position:0% +the general form K to S + 1/ s^ 2 the k/ + + + align:start position:0% +the general form K to S + 1/ s^ 2 the k/ +s^2 would give us the 1/ s^2 roll off at + + align:start position:0% +s^2 would give us the 1/ s^2 roll off at + + + align:start position:0% +s^2 would give us the 1/ s^2 roll off at +low frequencies we then put in a zero + + align:start position:0% +low frequencies we then put in a zero + + + align:start position:0% +low frequencies we then put in a zero +which causes our Loop transmission to go + + align:start position:0% +which causes our Loop transmission to go + + + align:start position:0% +which causes our Loop transmission to go +as 1/ s in the vicinity of crossover uh + + align:start position:0% +as 1/ s in the vicinity of crossover uh + + + align:start position:0% +as 1/ s in the vicinity of crossover uh +hopefully getting enough phase margin + + align:start position:0% +hopefully getting enough phase margin + + + align:start position:0% +hopefully getting enough phase margin +for acceptably stable + + align:start position:0% + + + + align:start position:0% + +performance in this case we really have + + align:start position:0% +performance in this case we really have + + + align:start position:0% +performance in this case we really have +to use a two-port network in order to + + align:start position:0% +to use a two-port network in order to + + + align:start position:0% +to use a two-port network in order to +achieve our desired short circuit + + align:start position:0% +achieve our desired short circuit + + + align:start position:0% +achieve our desired short circuit +transfer admittance we want to get a + + align:start position:0% +transfer admittance we want to get a + + + align:start position:0% +transfer admittance we want to get a +short circuit transfer admittance of the + + align:start position:0% +short circuit transfer admittance of the + + + align:start position:0% +short circuit transfer admittance of the +form some constant time s^2 over to s+ + + align:start position:0% +form some constant time s^2 over to s+ + + + align:start position:0% +form some constant time s^2 over to s+ +one we can't do that as a with a single + + align:start position:0% +one we can't do that as a with a single + + + align:start position:0% +one we can't do that as a with a single +element as we did in the case of one + + align:start position:0% +element as we did in the case of one + + + align:start position:0% +element as we did in the case of one +pole compensation + + align:start position:0% +pole compensation + + + align:start position:0% +pole compensation +where we wanted a short circuit transfer + + align:start position:0% +where we wanted a short circuit transfer + + + align:start position:0% +where we wanted a short circuit transfer +ad admittance just proportional to + + align:start position:0% +ad admittance just proportional to + + + align:start position:0% +ad admittance just proportional to +S we can + + align:start position:0% +S we can + + + align:start position:0% +S we can +however + + align:start position:0% +however + + + align:start position:0% +however +get the desired form for the short + + align:start position:0% +get the desired form for the short + + + align:start position:0% +get the desired form for the short +circuit transfer admittance out of a t + + align:start position:0% +circuit transfer admittance out of a t + + + align:start position:0% +circuit transfer admittance out of a t +Network as shown here we have two + + align:start position:0% +Network as shown here we have two + + + align:start position:0% +Network as shown here we have two +capacitors a single resistor uh if we + + align:start position:0% +capacitors a single resistor uh if we + + + align:start position:0% +capacitors a single resistor uh if we +measure the ratio of I subn to V subn we + + align:start position:0% +measure the ratio of I subn to V subn we + + + align:start position:0% +measure the ratio of I subn to V subn we +find out it has a desired form some + + align:start position:0% +find out it has a desired form some + + + align:start position:0% +find out it has a desired form some +constant times s s over another constant + + align:start position:0% +constant times s s over another constant + + + align:start position:0% +constant times s s over another constant +Time s + one and by appropriately + + align:start position:0% +Time s + one and by appropriately + + + align:start position:0% +Time s + one and by appropriately +choosing C1 C2 and R we can adjust the + + align:start position:0% +choosing C1 C2 and R we can adjust the + + + align:start position:0% +choosing C1 C2 and R we can adjust the +constants so this kind of a t network uh + + align:start position:0% +constants so this kind of a t network uh + + + align:start position:0% +constants so this kind of a t network uh +will in fact give us the sort of + + align:start position:0% +will in fact give us the sort of + + + align:start position:0% +will in fact give us the sort of +two-pole rolloff that we'd like to have + + align:start position:0% +two-pole rolloff that we'd like to have + + + align:start position:0% +two-pole rolloff that we'd like to have +if we use that kind of a network for + + align:start position:0% +if we use that kind of a network for + + + align:start position:0% +if we use that kind of a network for +compensation the + + align:start position:0% +compensation the + + + align:start position:0% +compensation the +effect on the amplifier transfer + + align:start position:0% +effect on the amplifier transfer + + + align:start position:0% +effect on the amplifier transfer +function again uh assuming an + + align:start position:0% +function again uh assuming an + + + align:start position:0% +function again uh assuming an +uncompensated transfer function + + align:start position:0% +uncompensated transfer function + + + align:start position:0% +uncompensated transfer function +including loading that's sort of three + + align:start position:0% +including loading that's sort of three + + + align:start position:0% +including loading that's sort of three +pole here's the 1 / s s 1/ s + + align:start position:0% +pole here's the 1 / s s 1/ s + + + align:start position:0% +pole here's the 1 / s s 1/ s +approximation and again we use the we + + align:start position:0% +approximation and again we use the we + + + align:start position:0% +approximation and again we use the we +get the lower of those two curves at all + + align:start position:0% +get the lower of those two curves at all + + + align:start position:0% +get the lower of those two curves at all +frequencies uh here we might argue that + + align:start position:0% +frequencies uh here we might argue that + + + align:start position:0% +frequencies uh here we might argue that +between about this + + align:start position:0% +between about this + + + align:start position:0% +between about this +frequency and this one the approximation + + align:start position:0% +frequency and this one the approximation + + + align:start position:0% +frequency and this one the approximation +the 1 / S2 and then a zero kind of + + align:start position:0% +the 1 / S2 and then a zero kind of + + + align:start position:0% +the 1 / S2 and then a zero kind of +approximation very accurately predict + + align:start position:0% +approximation very accurately predict + + + align:start position:0% +approximation very accurately predict +the behavior of the amplifier so the + + align:start position:0% +the behavior of the amplifier so the + + + align:start position:0% +the behavior of the amplifier so the +hope is that we'd have the crossover in + + align:start position:0% +hope is that we'd have the crossover in + + + align:start position:0% +hope is that we'd have the crossover in +our major Loop would occur somewhere in + + align:start position:0% +our major Loop would occur somewhere in + + + align:start position:0% +our major Loop would occur somewhere in +this region we could use the + + align:start position:0% +this region we could use the + + + align:start position:0% +this region we could use the +approximation to predict Behavior if we + + align:start position:0% +approximation to predict Behavior if we + + + align:start position:0% +approximation to predict Behavior if we +look at the angle we see a pattern + + align:start position:0% +look at the angle we see a pattern + + + align:start position:0% +look at the angle we see a pattern +that's very much like that which results + + align:start position:0% +that's very much like that which results + + + align:start position:0% +that's very much like that which results +with lag + + align:start position:0% +with lag + + + align:start position:0% +with lag +compensation uh the compensated angle + + align:start position:0% +compensation uh the compensated angle + + + align:start position:0% +compensation uh the compensated angle +dips down close to minus 180° possibly + + align:start position:0% +dips down close to minus 180° possibly + + + align:start position:0% +dips down close to minus 180° possibly +if this range of frequencies is + + align:start position:0% +if this range of frequencies is + + + align:start position:0% +if this range of frequencies is +large uh comes back back up in the + + align:start position:0% +large uh comes back back up in the + + + align:start position:0% +large uh comes back back up in the +vicinity of crossover crossover is + + align:start position:0% +vicinity of crossover crossover is + + + align:start position:0% +vicinity of crossover crossover is +assumed to occur crossover in the major + + align:start position:0% +assumed to occur crossover in the major + + + align:start position:0% +assumed to occur crossover in the major +Loop is assumed to occur in here + + align:start position:0% +Loop is assumed to occur in here + + + align:start position:0% +Loop is assumed to occur in here +somewhere comes back up so that we get + + align:start position:0% +somewhere comes back up so that we get + + + align:start position:0% +somewhere comes back up so that we get +adequate phase margin at crossover and + + align:start position:0% +adequate phase margin at crossover and + + + align:start position:0% +adequate phase margin at crossover and +then eventually Trails off this is the + + align:start position:0% +then eventually Trails off this is the + + + align:start position:0% +then eventually Trails off this is the +kind of a pattern that we very + + align:start position:0% +kind of a pattern that we very + + + align:start position:0% +kind of a pattern that we very +frequently get with lag compensation so + + align:start position:0% +frequently get with lag compensation so + + + align:start position:0% +frequently get with lag compensation so +the 1/ S squ sort of minor Loop + + align:start position:0% +the 1/ S squ sort of minor Loop + + + align:start position:0% +the 1/ S squ sort of minor Loop +compensation or the kind of minor Loop + + align:start position:0% +compensation or the kind of minor Loop + + + align:start position:0% +compensation or the kind of minor Loop +compensation that forces a 1/ s squ + + align:start position:0% +compensation that forces a 1/ s squ + + + align:start position:0% +compensation that forces a 1/ s squ +rolloff over a wide range of frequencies + + align:start position:0% +rolloff over a wide range of frequencies + + + align:start position:0% +rolloff over a wide range of frequencies +is sort of the parallel to lag + + align:start position:0% +is sort of the parallel to lag + + + align:start position:0% +is sort of the parallel to lag +compensation in the series compensated + + align:start position:0% +compensation in the series compensated + + + align:start position:0% +compensation in the series compensated +case again I'd like to look at the + + align:start position:0% +case again I'd like to look at the + + + align:start position:0% +case again I'd like to look at the +effects of of using or the results of + + align:start position:0% +effects of of using or the results of + + + align:start position:0% +effects of of using or the results of +using 1/ S2 + + align:start position:0% +using 1/ S2 + + + align:start position:0% +using 1/ S2 +compensation uh here we have + + align:start position:0% +compensation uh here we have + + + align:start position:0% +compensation uh here we have +another part in our in our system + + align:start position:0% +another part in our in our system + + + align:start position:0% +another part in our in our system +another portion where we have the + + align:start position:0% +another portion where we have the + + + align:start position:0% +another portion where we have the +amplifier uh that allows us to you look + + align:start position:0% +amplifier uh that allows us to you look + + + align:start position:0% +amplifier uh that allows us to you look +at 1/s squared compensation uh we we use + + align:start position:0% +at 1/s squared compensation uh we we use + + + align:start position:0% +at 1/s squared compensation uh we we use +a a somewhat different configuration + + align:start position:0% +a a somewhat different configuration + + + align:start position:0% +a a somewhat different configuration +here actually uh we use the amplifier + + align:start position:0% +here actually uh we use the amplifier + + + align:start position:0% +here actually uh we use the amplifier +connected as a Unity gain inverter and + + align:start position:0% +connected as a Unity gain inverter and + + + align:start position:0% +connected as a Unity gain inverter and +the reason for that is that we're able + + align:start position:0% +the reason for that is that we're able + + + align:start position:0% +the reason for that is that we're able +to very easily look at the error signal + + align:start position:0% +to very easily look at the error signal + + + align:start position:0% +to very easily look at the error signal +we connect the the amplifier as a Unity + + align:start position:0% +we connect the the amplifier as a Unity + + + align:start position:0% +we connect the the amplifier as a Unity +gain inverter and let me if I can look + + align:start position:0% +gain inverter and let me if I can look + + + align:start position:0% +gain inverter and let me if I can look +at at a view graph that shows that + + align:start position:0% + + + + align:start position:0% + +topology uh here's the configuration we + + align:start position:0% +topology uh here's the configuration we + + + align:start position:0% +topology uh here's the configuration we +simply have an equal valued input and + + align:start position:0% +simply have an equal valued input and + + + align:start position:0% +simply have an equal valued input and +feedback resistor we have the T Network + + align:start position:0% +feedback resistor we have the T Network + + + align:start position:0% +feedback resistor we have the T Network +that does compensation in this case we + + align:start position:0% +that does compensation in this case we + + + align:start position:0% +that does compensation in this case we +chose elements in the t uh so that Unity + + align:start position:0% +chose elements in the t uh so that Unity + + + align:start position:0% +chose elements in the t uh so that Unity +gain frequency in the amplifier uh is + + align:start position:0% +gain frequency in the amplifier uh is + + + align:start position:0% +gain frequency in the amplifier uh is +about 1 and a 12 megahertz the 2:1 + + align:start position:0% +about 1 and a 12 megahertz the 2:1 + + + align:start position:0% +about 1 and a 12 megahertz the 2:1 +attenuation provided by the feedback + + align:start position:0% +attenuation provided by the feedback + + + align:start position:0% +attenuation provided by the feedback +Network forces overall crossover uh at + + align:start position:0% +Network forces overall crossover uh at + + + align:start position:0% +Network forces overall crossover uh at +about uh uh 1 MHz or or something like + + align:start position:0% +about uh uh 1 MHz or or something like + + + align:start position:0% +about uh uh 1 MHz or or something like +that uh the zero uh comes in at at about + + align:start position:0% +that uh the zero uh comes in at at about + + + align:start position:0% +that uh the zero uh comes in at at about + + align:start position:0% + + + align:start position:0% +kilohertz uh so + + align:start position:0% +kilohertz uh so + + + align:start position:0% +kilohertz uh so +this combination of values as we say + + align:start position:0% +this combination of values as we say + + + align:start position:0% +this combination of values as we say +gives us the 1/ s^ squ rolloff breaks + + align:start position:0% +gives us the 1/ s^ squ rolloff breaks + + + align:start position:0% +gives us the 1/ s^ squ rolloff breaks +back to 1 / s in the vicinity of + + align:start position:0% +back to 1 / s in the vicinity of + + + align:start position:0% +back to 1 / s in the vicinity of +crossover and the advantage of the + + align:start position:0% +crossover and the advantage of the + + + align:start position:0% +crossover and the advantage of the +inverter topology as opposed to the + + align:start position:0% +inverter topology as opposed to the + + + align:start position:0% +inverter topology as opposed to the +non-inverting configuration we used + + align:start position:0% +non-inverting configuration we used + + + align:start position:0% +non-inverting configuration we used +earlier is that the signal at this point + + align:start position:0% +earlier is that the signal at this point + + + align:start position:0% +earlier is that the signal at this point +is a direct measure of the error in the + + align:start position:0% +is a direct measure of the error in the + + + align:start position:0% +is a direct measure of the error in the +system we can look at this point with an + + align:start position:0% +system we can look at this point with an + + + align:start position:0% +system we can look at this point with an +oscilloscope and ideally this voltage + + align:start position:0% +oscilloscope and ideally this voltage + + + align:start position:0% +oscilloscope and ideally this voltage +should be zero uh the output should + + align:start position:0% +should be zero uh the output should + + + align:start position:0% +should be zero uh the output should +ideally be the negative of the input uh + + align:start position:0% +ideally be the negative of the input uh + + + align:start position:0% +ideally be the negative of the input uh +assuming no loading by the amplifier + + align:start position:0% +assuming no loading by the amplifier + + + align:start position:0% +assuming no loading by the amplifier +this point uh should reflect error + + align:start position:0% +this point uh should reflect error + + + align:start position:0% +this point uh should reflect error +directly if the I output were exactly + + align:start position:0% +directly if the I output were exactly + + + align:start position:0% +directly if the I output were exactly +the negative of the input this point + + align:start position:0% +the negative of the input this point + + + align:start position:0% +the negative of the input this point +would be at zero to the extent that it's + + align:start position:0% +would be at zero to the extent that it's + + + align:start position:0% +would be at zero to the extent that it's +not we get a direct measure of error and + + align:start position:0% +not we get a direct measure of error and + + + align:start position:0% +not we get a direct measure of error and +so this configuration allows us to + + align:start position:0% +so this configuration allows us to + + + align:start position:0% +so this configuration allows us to +readly look at the error of the system + + align:start position:0% +readly look at the error of the system + + + align:start position:0% +readly look at the error of the system +and that's the reason that we use it in + + align:start position:0% +and that's the reason that we use it in + + + align:start position:0% +and that's the reason that we use it in +preference to the non-inverting + + align:start position:0% +preference to the non-inverting + + + align:start position:0% +preference to the non-inverting +configuration so as I say we have that + + align:start position:0% +configuration so as I say we have that + + + align:start position:0% +configuration so as I say we have that +amplifier here we have a buffer + + align:start position:0% +amplifier here we have a buffer + + + align:start position:0% +amplifier here we have a buffer +amplifier wi that allows us to look at + + align:start position:0% +amplifier wi that allows us to look at + + + align:start position:0% +amplifier wi that allows us to look at +the error signal and present that signal + + align:start position:0% +the error signal and present that signal + + + align:start position:0% +the error signal and present that signal +on an oscilloscope when we wish + + align:start position:0% +on an oscilloscope when we wish + + + align:start position:0% +on an oscilloscope when we wish +to and we're able to very quickly change + + align:start position:0% +to and we're able to very quickly change + + + align:start position:0% +to and we're able to very quickly change +from 1 /s to 1/ s^ squ compensation + + align:start position:0% +from 1 /s to 1/ s^ squ compensation + + + align:start position:0% +from 1 /s to 1/ s^ squ compensation +maintaining crossover frequency by + + align:start position:0% +maintaining crossover frequency by + + + align:start position:0% +maintaining crossover frequency by +simply lifting the resistor in the + + align:start position:0% +simply lifting the resistor in the + + + align:start position:0% +simply lifting the resistor in the +middle leg of the + + align:start position:0% + + + + align:start position:0% + +T we're first going to look at the small + + align:start position:0% +T we're first going to look at the small + + + align:start position:0% +T we're first going to look at the small +signal response of the amplifier uh and + + align:start position:0% +signal response of the amplifier uh and + + + align:start position:0% +signal response of the amplifier uh and +let's look first at what happens with + + align:start position:0% +let's look first at what happens with + + + align:start position:0% +let's look first at what happens with +1/s + + align:start position:0% +1/s + + + align:start position:0% +1/s +compensation uh here we have removed the + + align:start position:0% +compensation uh here we have removed the + + + align:start position:0% +compensation uh here we have removed the +resistor in the T network uh simply + + align:start position:0% +resistor in the T network uh simply + + + align:start position:0% +resistor in the T network uh simply +switched it out open circuited the + + align:start position:0% +switched it out open circuited the + + + align:start position:0% +switched it out open circuited the +resistor and we get the rise time that + + align:start position:0% +resistor and we get the rise time that + + + align:start position:0% +resistor and we get the rise time that +we we + + align:start position:0% +we we + + + align:start position:0% +we we +show uh let me see if I can make things + + align:start position:0% +show uh let me see if I can make things + + + align:start position:0% +show uh let me see if I can make things +go just a little bit faster + + align:start position:0% +go just a little bit faster + + + align:start position:0% +go just a little bit faster +here uh we get a rise time in this case + + align:start position:0% +here uh we get a rise time in this case + + + align:start position:0% +here uh we get a rise time in this case +of of a couple of 100 nond 300 nond + + align:start position:0% +of of a couple of 100 nond 300 nond + + + align:start position:0% +of of a couple of 100 nond 300 nond +something like that reflecting roughly a + + align:start position:0% +something like that reflecting roughly a + + + align:start position:0% +something like that reflecting roughly a +megahertz crossover reasonably well + + align:start position:0% +megahertz crossover reasonably well + + + align:start position:0% +megahertz crossover reasonably well +damped response uh if we switch to 1 s^ + + align:start position:0% +damped response uh if we switch to 1 s^ + + + align:start position:0% +damped response uh if we switch to 1 s^ +s compensation the zero is back I think + + align:start position:0% +s compensation the zero is back I think + + + align:start position:0% +s compensation the zero is back I think +actually if we go through the numbers + + align:start position:0% +actually if we go through the numbers + + + align:start position:0% +actually if we go through the numbers +for this network the zero is back about + + align:start position:0% +for this network the zero is back about + + + align:start position:0% +for this network the zero is back about +a factor of five or six or seven from + + align:start position:0% +a factor of five or six or seven from + + + align:start position:0% +a factor of five or six or seven from +crossover we notice very little change + + align:start position:0% +crossover we notice very little change + + + align:start position:0% +crossover we notice very little change +as I go from 1 / s to 1 / s^2 + + align:start position:0% +as I go from 1 / s to 1 / s^2 + + + align:start position:0% +as I go from 1 / s to 1 / s^2 +compensation very little change in the + + align:start position:0% +compensation very little change in the + + + align:start position:0% +compensation very little change in the +relative stability the phase margin of + + align:start position:0% +relative stability the phase margin of + + + align:start position:0% +relative stability the phase margin of +the two systems is is very nearly + + align:start position:0% +the two systems is is very nearly + + + align:start position:0% +the two systems is is very nearly +comparable the zero is located well + + align:start position:0% +comparable the zero is located well + + + align:start position:0% +comparable the zero is located well +enough below crossover the equivalent to + + align:start position:0% +enough below crossover the equivalent to + + + align:start position:0% +enough below crossover the equivalent to +locating the zero of a lag Network far + + align:start position:0% +locating the zero of a lag Network far + + + align:start position:0% +locating the zero of a lag Network far +enough below crossover uh so that the + + align:start position:0% +enough below crossover uh so that the + + + align:start position:0% +enough below crossover uh so that the +stability is comparable uh there is one + + align:start position:0% +stability is comparable uh there is one + + + align:start position:0% +stability is comparable uh there is one +effect that I'll point out and we'll + + align:start position:0% +effect that I'll point out and we'll + + + align:start position:0% +effect that I'll point out and we'll +talk + + align:start position:0% +talk + + + align:start position:0% +talk +about + + align:start position:0% +about + + + align:start position:0% +about +later notice that when we use 1/s + + align:start position:0% +later notice that when we use 1/s + + + align:start position:0% +later notice that when we use 1/s +compensation the response goes up to + + align:start position:0% +compensation the response goes up to + + + align:start position:0% +compensation the response goes up to +final value pretty much settles there uh + + align:start position:0% +final value pretty much settles there uh + + + align:start position:0% +final value pretty much settles there uh +and the speed of the response is is + + align:start position:0% +and the speed of the response is is + + + align:start position:0% +and the speed of the response is is +compatible with the 1 mahz crossover + + align:start position:0% +compatible with the 1 mahz crossover + + + align:start position:0% +compatible with the 1 mahz crossover +frequency if I use 1/ s^2 compensation + + align:start position:0% +frequency if I use 1/ s^2 compensation + + + align:start position:0% +frequency if I use 1/ s^2 compensation +the basic response is very much the same + + align:start position:0% +the basic response is very much the same + + + align:start position:0% +the basic response is very much the same +the relative stability is very much the + + align:start position:0% +the relative stability is very much the + + + align:start position:0% +the relative stability is very much the +same but we notice a a sort of long + + align:start position:0% +same but we notice a a sort of long + + + align:start position:0% +same but we notice a a sort of long +tail uh we can see that let me up the + + align:start position:0% +tail uh we can see that let me up the + + + align:start position:0% +tail uh we can see that let me up the +amplitude just a little + + align:start position:0% +amplitude just a little + + + align:start position:0% +amplitude just a little +bit + + align:start position:0% +bit + + + align:start position:0% +bit +and look at + + align:start position:0% +and look at + + + align:start position:0% +and look at +the final part of the response we notice + + align:start position:0% +the final part of the response we notice + + + align:start position:0% +the final part of the response we notice +a fairly prolonged tail uh the time + + align:start position:0% +a fairly prolonged tail uh the time + + + align:start position:0% +a fairly prolonged tail uh the time +constant associated with that taale is + + align:start position:0% +constant associated with that taale is + + + align:start position:0% +constant associated with that taale is +somewhere on the order of a microsc + + align:start position:0% +somewhere on the order of a microsc + + + align:start position:0% +somewhere on the order of a microsc +we're at a a 500 NCS per Division and + + align:start position:0% +we're at a a 500 NCS per Division and + + + align:start position:0% +we're at a a 500 NCS per Division and +from here to here the tail May shrink by + + align:start position:0% +from here to here the tail May shrink by + + + align:start position:0% +from here to here the tail May shrink by +to one minus one over e of final value + + align:start position:0% +to one minus one over e of final value + + + align:start position:0% +to one minus one over e of final value +so uh we have a time constant of roughly + + align:start position:0% +so uh we have a time constant of roughly + + + align:start position:0% +so uh we have a time constant of roughly +a microsc we'll have more to say about + + align:start position:0% +a microsc we'll have more to say about + + + align:start position:0% +a microsc we'll have more to say about +that in a little while but that's the + + align:start position:0% +that in a little while but that's the + + + align:start position:0% +that in a little while but that's the +only really noticeable difference that + + align:start position:0% +only really noticeable difference that + + + align:start position:0% +only really noticeable difference that +we see in the small signal input to + + align:start position:0% +we see in the small signal input to + + + align:start position:0% +we see in the small signal input to +Output step responses of the + + align:start position:0% +Output step responses of the + + + align:start position:0% +Output step responses of the +system now let's look at at errors for + + align:start position:0% +system now let's look at at errors for + + + align:start position:0% +system now let's look at at errors for +certain kinds of inputs or for one input + + align:start position:0% +certain kinds of inputs or for one input + + + align:start position:0% +certain kinds of inputs or for one input +in particular what I'd like to do is + + align:start position:0% +in particular what I'd like to do is + + + align:start position:0% +in particular what I'd like to do is +drive the system with a triangle wave + + align:start position:0% +drive the system with a triangle wave + + + align:start position:0% +drive the system with a triangle wave +Drive our amplifier with a triangle + + align:start position:0% + + + + align:start position:0% + +wave and let's put in a a much larger + + align:start position:0% +wave and let's put in a a much larger + + + align:start position:0% +wave and let's put in a a much larger +one than we now have + + align:start position:0% + + + + align:start position:0% + +uh let's begin to go + + align:start position:0% + + + + align:start position:0% + +up uh in fact this amplifier has an + + align:start position:0% +up uh in fact this amplifier has an + + + align:start position:0% +up uh in fact this amplifier has an +output dynamic range of about plus or + + align:start position:0% +output dynamic range of about plus or + + + align:start position:0% +output dynamic range of about plus or +minus 10 volts and let's drive very + + align:start position:0% +minus 10 volts and let's drive very + + + align:start position:0% +minus 10 volts and let's drive very +close to that here we are at 5 volts per + + align:start position:0% +close to that here we are at 5 volts per + + + align:start position:0% +close to that here we are at 5 volts per +division let me run the input amplitude + + align:start position:0% +division let me run the input amplitude + + + align:start position:0% +division let me run the input amplitude +up to the point where we're getting an + + align:start position:0% +up to the point where we're getting an + + + align:start position:0% +up to the point where we're getting an +output + + align:start position:0% +output + + + align:start position:0% +output +amplitude of about 20 volts Peak to Peak + + align:start position:0% +amplitude of about 20 volts Peak to Peak + + + align:start position:0% +amplitude of about 20 volts Peak to Peak +plus or minus 10 volts so let's move + + align:start position:0% +plus or minus 10 volts so let's move + + + align:start position:0% +plus or minus 10 volts so let's move +that up in there so that's the the input + + align:start position:0% +that up in there so that's the the input + + + align:start position:0% +that up in there so that's the the input +signal and the output signal really to + + align:start position:0% +signal and the output signal really to + + + align:start position:0% +signal and the output signal really to +the amplifier to a good degree of + + align:start position:0% +the amplifier to a good degree of + + + align:start position:0% +the amplifier to a good degree of +approximation the output signal which is + + align:start position:0% +approximation the output signal which is + + + align:start position:0% +approximation the output signal which is +the one we're actually looking at is + + align:start position:0% +the one we're actually looking at is + + + align:start position:0% +the one we're actually looking at is +simply the negative of the input signal + + align:start position:0% +simply the negative of the input signal + + + align:start position:0% +simply the negative of the input signal +so there's our triangle uh we're running + + align:start position:0% +so there's our triangle uh we're running + + + align:start position:0% +so there's our triangle uh we're running +now at about uh 5 kohtz were 50 microc + + align:start position:0% +now at about uh 5 kohtz were 50 microc + + + align:start position:0% +now at about uh 5 kohtz were 50 microc +per division uh the period of this + + align:start position:0% +per division uh the period of this + + + align:start position:0% +per division uh the period of this +waveform is about four divisions or 200 + + align:start position:0% +waveform is about four divisions or 200 + + + align:start position:0% +waveform is about four divisions or 200 +micros seconds so we get the uh we're + + align:start position:0% +micros seconds so we get the uh we're + + + align:start position:0% +micros seconds so we get the uh we're +running at about 5 khz let's first look + + align:start position:0% +running at about 5 khz let's first look + + + align:start position:0% +running at about 5 khz let's first look +at the error signal when we have 1/s + + align:start position:0% +at the error signal when we have 1/s + + + align:start position:0% +at the error signal when we have 1/s +compensation uh we have the error signal + + align:start position:0% +compensation uh we have the error signal + + + align:start position:0% +compensation uh we have the error signal +on the second Channel and let me put + + align:start position:0% +on the second Channel and let me put + + + align:start position:0% +on the second Channel and let me put +that on + + align:start position:0% + + + + align:start position:0% + +simultaneously uh we need + + align:start position:0% +simultaneously uh we need + + + align:start position:0% +simultaneously uh we need +a much + + align:start position:0% +a much + + + align:start position:0% +a much +larger look at much smaller signals here + + align:start position:0% +larger look at much smaller signals here + + + align:start position:0% +larger look at much smaller signals here +a much higher scale + + align:start position:0% + + + + align:start position:0% + +factor and what we see is an error + + align:start position:0% +factor and what we see is an error + + + align:start position:0% +factor and what we see is an error +signal let's get a zero line for that + + align:start position:0% +signal let's get a zero line for that + + + align:start position:0% +signal let's get a zero line for that +right + + align:start position:0% + + + + align:start position:0% + +there what we see is an error signal + + align:start position:0% +there what we see is an error signal + + + align:start position:0% +there what we see is an error signal +that's very very nearly a square wave it + + align:start position:0% +that's very very nearly a square wave it + + + align:start position:0% +that's very very nearly a square wave it +goes let's say we're at 10 molts per + + align:start position:0% +goes let's say we're at 10 molts per + + + align:start position:0% +goes let's say we're at 10 molts per +division uh and so it goes somewhere on + + align:start position:0% +division uh and so it goes somewhere on + + + align:start position:0% +division uh and so it goes somewhere on +the order of plus 15 molts and minus5 + + align:start position:0% +the order of plus 15 molts and minus5 + + + align:start position:0% +the order of plus 15 molts and minus5 +molts is that + + align:start position:0% + + + + align:start position:0% + +reasonable well let's see we said that + + align:start position:0% +reasonable well let's see we said that + + + align:start position:0% +reasonable well let's see we said that +when we use single pole + + align:start position:0% +when we use single pole + + + align:start position:0% +when we use single pole +compensation the open loop transfer + + align:start position:0% +compensation the open loop transfer + + + align:start position:0% +compensation the open loop transfer +function of the operational amplifier + + align:start position:0% +function of the operational amplifier + + + align:start position:0% +function of the operational amplifier +over a wide range of frequencies is + + align:start position:0% +over a wide range of frequencies is + + + align:start position:0% +over a wide range of frequencies is +proportional to 1 / s that's what we + + align:start position:0% +proportional to 1 / s that's what we + + + align:start position:0% +proportional to 1 / s that's what we +mean by having a single pole roll off + + align:start position:0% +mean by having a single pole roll off + + + align:start position:0% +mean by having a single pole roll off +the amplifier looks sort of like an an + + align:start position:0% +the amplifier looks sort of like an an + + + align:start position:0% +the amplifier looks sort of like an an +integrator from its input terminals its + + align:start position:0% +integrator from its input terminals its + + + align:start position:0% +integrator from its input terminals its +differential input terminals to its + + align:start position:0% +differential input terminals to its + + + align:start position:0% +differential input terminals to its +output or alternatively the output + + align:start position:0% +output or alternatively the output + + + align:start position:0% +output or alternatively the output +voltage of the amplifier is the integral + + align:start position:0% +voltage of the amplifier is the integral + + + align:start position:0% +voltage of the amplifier is the integral +of the voltage applied at its input at + + align:start position:0% +of the voltage applied at its input at + + + align:start position:0% +of the voltage applied at its input at +the very input terminals in the + + align:start position:0% +the very input terminals in the + + + align:start position:0% +the very input terminals in the +amplifier not the input of the overall + + align:start position:0% +amplifier not the input of the overall + + + align:start position:0% +amplifier not the input of the overall +feedback loop fine if we have a triangle + + align:start position:0% +feedback loop fine if we have a triangle + + + align:start position:0% +feedback loop fine if we have a triangle +wave at the output and that's the + + align:start position:0% +wave at the output and that's the + + + align:start position:0% +wave at the output and that's the +integral of the input the input of + + align:start position:0% +integral of the input the input of + + + align:start position:0% +integral of the input the input of +course is the derivative with some scale + + align:start position:0% +course is the derivative with some scale + + + align:start position:0% +course is the derivative with some scale +factor of that output signal we have a + + align:start position:0% +factor of that output signal we have a + + + align:start position:0% +factor of that output signal we have a +triangle wave at the output we have a + + align:start position:0% +triangle wave at the output we have a + + + align:start position:0% +triangle wave at the output we have a +square wave at the input so this is + + align:start position:0% +square wave at the input so this is + + + align:start position:0% +square wave at the input so this is +perfectly reason able this is the sort + + align:start position:0% +perfectly reason able this is the sort + + + align:start position:0% +perfectly reason able this is the sort +of of response we'd + + align:start position:0% +of of response we'd + + + align:start position:0% +of of response we'd +anticipate if we uh got a triangle wave + + align:start position:0% +anticipate if we uh got a triangle wave + + + align:start position:0% +anticipate if we uh got a triangle wave +or have force a triangle wave at the + + align:start position:0% +or have force a triangle wave at the + + + align:start position:0% +or have force a triangle wave at the +output uh and have an amplifier whose + + align:start position:0% +output uh and have an amplifier whose + + + align:start position:0% +output uh and have an amplifier whose +open loop transfer function rolls off as + + align:start position:0% +open loop transfer function rolls off as + + + align:start position:0% +open loop transfer function rolls off as +1/ + + align:start position:0% +1/ + + + align:start position:0% +1/ +s now let's see what happens when we + + align:start position:0% +s now let's see what happens when we + + + align:start position:0% +s now let's see what happens when we +switch to 1 / s^2 compensation so to do + + align:start position:0% +switch to 1 / s^2 compensation so to do + + + align:start position:0% +switch to 1 / s^2 compensation so to do +that I will simply throw this + + align:start position:0% +that I will simply throw this + + + align:start position:0% +that I will simply throw this +switch and notice that + + align:start position:0% +switch and notice that + + + align:start position:0% +switch and notice that +the error most of the time gets much + + align:start position:0% +the error most of the time gets much + + + align:start position:0% +the error most of the time gets much +smaller there are a series of of really + + align:start position:0% +smaller there are a series of of really + + + align:start position:0% +smaller there are a series of of really +what amount to impulses that we can't + + align:start position:0% +what amount to impulses that we can't + + + align:start position:0% +what amount to impulses that we can't +see very well let's see if we can + + align:start position:0% +see very well let's see if we can + + + align:start position:0% +see very well let's see if we can +brighten them up uh there's a series of + + align:start position:0% + + + + align:start position:0% + +impulses here here here here + + align:start position:0% +impulses here here here here + + + align:start position:0% +impulses here here here here +here and the rest of the time the error + + align:start position:0% +here and the rest of the time the error + + + align:start position:0% +here and the rest of the time the error +is very very nearly zero to within our + + align:start position:0% +is very very nearly zero to within our + + + align:start position:0% +is very very nearly zero to within our +our ability to measure it this line is + + align:start position:0% +our ability to measure it this line is + + + align:start position:0% +our ability to measure it this line is +zero does do that make + + align:start position:0% +zero does do that make + + + align:start position:0% +zero does do that make +sense well here we we have changed the + + align:start position:0% +sense well here we we have changed the + + + align:start position:0% +sense well here we we have changed the +amplifier so that over a wide range of + + align:start position:0% +amplifier so that over a wide range of + + + align:start position:0% +amplifier so that over a wide range of +frequencies its open loop transfer + + align:start position:0% +frequencies its open loop transfer + + + align:start position:0% +frequencies its open loop transfer +function falls off as 1 / S2 in other + + align:start position:0% +function falls off as 1 / S2 in other + + + align:start position:0% +function falls off as 1 / S2 in other +words over a wide range of frequencies + + align:start position:0% +words over a wide range of frequencies + + + align:start position:0% +words over a wide range of frequencies +the output is the second integral of the + + align:start position:0% +the output is the second integral of the + + + align:start position:0% +the output is the second integral of the +error signal or correspondingly the + + align:start position:0% +error signal or correspondingly the + + + align:start position:0% +error signal or correspondingly the +error signal is the second derivative of + + align:start position:0% +error signal is the second derivative of + + + align:start position:0% +error signal is the second derivative of +the output signal we have a series of + + align:start position:0% +the output signal we have a series of + + + align:start position:0% +the output signal we have a series of +ramps at the output a triangle wave at + + align:start position:0% +ramps at the output a triangle wave at + + + align:start position:0% +ramps at the output a triangle wave at +the output why we'd anticipate that that + + align:start position:0% +the output why we'd anticipate that that + + + align:start position:0% +the output why we'd anticipate that that +the input signal would be the second + + align:start position:0% +the input signal would be the second + + + align:start position:0% +the input signal would be the second +derivative of the triangle wave or a + + align:start position:0% +derivative of the triangle wave or a + + + align:start position:0% +derivative of the triangle wave or a +series of impulses of course they're not + + align:start position:0% +series of impulses of course they're not + + + align:start position:0% +series of impulses of course they're not +perfect impulses they don't go to + + align:start position:0% +perfect impulses they don't go to + + + align:start position:0% +perfect impulses they don't go to +infinity and all that uh reflecting the + + align:start position:0% +infinity and all that uh reflecting the + + + align:start position:0% +infinity and all that uh reflecting the +the fact that we don't have a 1 / s^ s + + align:start position:0% +the fact that we don't have a 1 / s^ s + + + align:start position:0% +the fact that we don't have a 1 / s^ s +transfer function at all frequencies but + + align:start position:0% +transfer function at all frequencies but + + + align:start position:0% +transfer function at all frequencies but +we get a series of of small + + align:start position:0% +we get a series of of small + + + align:start position:0% +we get a series of of small +impulses and the important point is that + + align:start position:0% +impulses and the important point is that + + + align:start position:0% +impulses and the important point is that +most of the time the error is much much + + align:start position:0% +most of the time the error is much much + + + align:start position:0% +most of the time the error is much much +lower for one over s^2 compensation than + + align:start position:0% +lower for one over s^2 compensation than + + + align:start position:0% +lower for one over s^2 compensation than +it is for 1 / s compensation that simply + + align:start position:0% +it is for 1 / s compensation that simply + + + align:start position:0% +it is for 1 / s compensation that simply +reflects the fact that the open loop + + align:start position:0% +reflects the fact that the open loop + + + align:start position:0% +reflects the fact that the open loop +transfer function with 1 / s^2 + + align:start position:0% +transfer function with 1 / s^2 + + + align:start position:0% +transfer function with 1 / s^2 +compensation is much much larger at many + + align:start position:0% +compensation is much much larger at many + + + align:start position:0% +compensation is much much larger at many +many + + align:start position:0% +many + + + align:start position:0% +many +frequencies uh recall that the + + align:start position:0% +frequencies uh recall that the + + + align:start position:0% +frequencies uh recall that the +comparison between the two was as shown + + align:start position:0% +comparison between the two was as shown + + + align:start position:0% +comparison between the two was as shown +here we have + + align:start position:0% +here we have + + + align:start position:0% +here we have +the orange curve showing the 1 / s s + + align:start position:0% +the orange curve showing the 1 / s s + + + align:start position:0% +the orange curve showing the 1 / s s +compensation the yellow curve showing + + align:start position:0% +compensation the yellow curve showing + + + align:start position:0% +compensation the yellow curve showing +the single pole + + align:start position:0% +the single pole + + + align:start position:0% +the single pole +compensation and over all of these + + align:start position:0% +compensation and over all of these + + + align:start position:0% +compensation and over all of these +frequencies we have have considerably + + align:start position:0% +frequencies we have have considerably + + + align:start position:0% +frequencies we have have considerably +higher open loop gain from the two-pole + + align:start position:0% +higher open loop gain from the two-pole + + + align:start position:0% +higher open loop gain from the two-pole +compensated amplifier we'd anticipate + + align:start position:0% +compensated amplifier we'd anticipate + + + align:start position:0% +compensated amplifier we'd anticipate +and prove the sensitivity for any signal + + align:start position:0% +and prove the sensitivity for any signal + + + align:start position:0% +and prove the sensitivity for any signal +where the majority of the signal + + align:start position:0% +where the majority of the signal + + + align:start position:0% +where the majority of the signal +frequency components lay in this region + + align:start position:0% +frequency components lay in this region + + + align:start position:0% +frequency components lay in this region +where most of the signal energy was + + align:start position:0% +where most of the signal energy was + + + align:start position:0% +where most of the signal energy was +concentrated in this region uh the + + align:start position:0% +concentrated in this region uh the + + + align:start position:0% +concentrated in this region uh the +triangle wave that we've chosen happens + + align:start position:0% +triangle wave that we've chosen happens + + + align:start position:0% +triangle wave that we've chosen happens +to be one like that where the 5 KZ + + align:start position:0% +to be one like that where the 5 KZ + + + align:start position:0% +to be one like that where the 5 KZ +fundamental and the appropriate + + align:start position:0% +fundamental and the appropriate + + + align:start position:0% +fundamental and the appropriate +harmonics lie in this region or most of + + align:start position:0% +harmonics lie in this region or most of + + + align:start position:0% +harmonics lie in this region or most of +them lie in this region we get greatly + + align:start position:0% +them lie in this region we get greatly + + + align:start position:0% +them lie in this region we get greatly +improved desensitivity a much small + + align:start position:0% +improved desensitivity a much small + + + align:start position:0% +improved desensitivity a much small +smaller error signal in the system in + + align:start position:0% +smaller error signal in the system in + + + align:start position:0% +smaller error signal in the system in +fact we haven't particularly cheated by + + align:start position:0% +fact we haven't particularly cheated by + + + align:start position:0% +fact we haven't particularly cheated by +by picking a particularly fortunate test + + align:start position:0% +by picking a particularly fortunate test + + + align:start position:0% +by picking a particularly fortunate test +signal if we uh uh use the sonoid + + align:start position:0% +signal if we uh uh use the sonoid + + + align:start position:0% +signal if we uh uh use the sonoid +anywhere from this frequency to this + + align:start position:0% +anywhere from this frequency to this + + + align:start position:0% +anywhere from this frequency to this +frequency the numbers here are are + + align:start position:0% +frequency the numbers here are are + + + align:start position:0% +frequency the numbers here are are +something like 10 Hertz and 100 or 150 + + align:start position:0% +something like 10 Hertz and 100 or 150 + + + align:start position:0% +something like 10 Hertz and 100 or 150 +ktz any signal in that region uh + + align:start position:0% +ktz any signal in that region uh + + + align:start position:0% +ktz any signal in that region uh +would or any signal whose dominant + + align:start position:0% +would or any signal whose dominant + + + align:start position:0% +would or any signal whose dominant +spectral components lay in that region + + align:start position:0% +spectral components lay in that region + + + align:start position:0% +spectral components lay in that region +would get a considerably smaller error + + align:start position:0% +would get a considerably smaller error + + + align:start position:0% +would get a considerably smaller error +signal with 1 / s squ compensation than + + align:start position:0% +signal with 1 / s squ compensation than + + + align:start position:0% +signal with 1 / s squ compensation than +with one /s + + align:start position:0% +with one /s + + + align:start position:0% +with one /s +compensation + + align:start position:0% +compensation + + + align:start position:0% +compensation +well why don't we always use 1/ s^ squ + + align:start position:0% +well why don't we always use 1/ s^ squ + + + align:start position:0% +well why don't we always use 1/ s^ squ +compensation one of the problems is it's + + align:start position:0% +compensation one of the problems is it's + + + align:start position:0% +compensation one of the problems is it's +nowhere near as general purpose the 1/ S + + align:start position:0% +nowhere near as general purpose the 1/ S + + + align:start position:0% +nowhere near as general purpose the 1/ S +squ compensation really has to be very + + align:start position:0% +squ compensation really has to be very + + + align:start position:0% +squ compensation really has to be very +carefully tailored to the particular + + align:start position:0% +carefully tailored to the particular + + + align:start position:0% +carefully tailored to the particular +application we have to cross over in the + + align:start position:0% +application we have to cross over in the + + + align:start position:0% +application we have to cross over in the +region where the open loop transfer + + align:start position:0% +region where the open loop transfer + + + align:start position:0% +region where the open loop transfer +function is dropping off as 1 / s if we + + align:start position:0% +function is dropping off as 1 / s if we + + + align:start position:0% +function is dropping off as 1 / s if we +cross over at lower free frequencies we + + align:start position:0% +cross over at lower free frequencies we + + + align:start position:0% +cross over at lower free frequencies we +run into a stability problem because of + + align:start position:0% +run into a stability problem because of + + + align:start position:0% +run into a stability problem because of +limited phase margin uh in the case of + + align:start position:0% +limited phase margin uh in the case of + + + align:start position:0% +limited phase margin uh in the case of +single pole compensation why we're able + + align:start position:0% +single pole compensation why we're able + + + align:start position:0% +single pole compensation why we're able +to if if we lower crossover frequency we + + align:start position:0% +to if if we lower crossover frequency we + + + align:start position:0% +to if if we lower crossover frequency we +the system becomes slower but stability + + align:start position:0% +the system becomes slower but stability + + + align:start position:0% +the system becomes slower but stability +isn't compromised however that's not the + + align:start position:0% +isn't compromised however that's not the + + + align:start position:0% +isn't compromised however that's not the +case with 1/ s squ so we have to be a + + align:start position:0% +case with 1/ s squ so we have to be a + + + align:start position:0% +case with 1/ s squ so we have to be a +little bit more careful in our choice we + + align:start position:0% +little bit more careful in our choice we + + + align:start position:0% +little bit more careful in our choice we +have to know the application somewhat + + align:start position:0% +have to know the application somewhat + + + align:start position:0% +have to know the application somewhat +better um another consideration is what + + align:start position:0% +better um another consideration is what + + + align:start position:0% +better um another consideration is what +happens if we somehow Force another pole + + align:start position:0% +happens if we somehow Force another pole + + + align:start position:0% +happens if we somehow Force another pole +in the loop suppose we could pass L load + + align:start position:0% +in the loop suppose we could pass L load + + + align:start position:0% +in the loop suppose we could pass L load +the amplifier which has the effect of + + align:start position:0% +the amplifier which has the effect of + + + align:start position:0% +the amplifier which has the effect of +forcing another pole if we do that why + + align:start position:0% +forcing another pole if we do that why + + + align:start position:0% +forcing another pole if we do that why +we find out that that with one over s + + align:start position:0% +we find out that that with one over s + + + align:start position:0% +we find out that that with one over s +squ compensation stability or + + align:start position:0% +squ compensation stability or + + + align:start position:0% +squ compensation stability or +instability is a very real possibility + + align:start position:0% +instability is a very real possibility + + + align:start position:0% +instability is a very real possibility +and because we can force crossover back + + align:start position:0% +and because we can force crossover back + + + align:start position:0% +and because we can force crossover back +to relatively lower frequencies where + + align:start position:0% +to relatively lower frequencies where + + + align:start position:0% +to relatively lower frequencies where +the amplifier even without the + + align:start position:0% +the amplifier even without the + + + align:start position:0% +the amplifier even without the +additional load has limited phase margin + + align:start position:0% +additional load has limited phase margin + + + align:start position:0% +additional load has limited phase margin +we then add the additional Pole from the + + align:start position:0% +we then add the additional Pole from the + + + align:start position:0% +we then add the additional Pole from the +load capacitor and instability is a very + + align:start position:0% +load capacitor and instability is a very + + + align:start position:0% +load capacitor and instability is a very +real possibility so there are those + + align:start position:0% +real possibility so there are those + + + align:start position:0% +real possibility so there are those +kinds of disadvantages but again if it's + + align:start position:0% +kinds of disadvantages but again if it's + + + align:start position:0% +kinds of disadvantages but again if it's +carefully chosen if we know the + + align:start position:0% +carefully chosen if we know the + + + align:start position:0% +carefully chosen if we know the +application we know what loads to + + align:start position:0% +application we know what loads to + + + align:start position:0% +application we know what loads to +anticipate we know the capacitors aren't + + align:start position:0% +anticipate we know the capacitors aren't + + + align:start position:0% +anticipate we know the capacitors aren't +included uh it it gives us very + + align:start position:0% +included uh it it gives us very + + + align:start position:0% +included uh it it gives us very +dramatically improved desensitivity as + + align:start position:0% +dramatically improved desensitivity as + + + align:start position:0% +dramatically improved desensitivity as +we've seen from the demonstration + + align:start position:0% +we've seen from the demonstration + + + align:start position:0% +we've seen from the demonstration +there's one final effect associated with + + align:start position:0% +there's one final effect associated with + + + align:start position:0% +there's one final effect associated with +either the two-pole compensation or the + + align:start position:0% +either the two-pole compensation or the + + + align:start position:0% +either the two-pole compensation or the +same sort of thing happens with lag + + align:start position:0% +same sort of thing happens with lag + + + align:start position:0% +same sort of thing happens with lag +compensation recall the sort of + + align:start position:0% +compensation recall the sort of + + + align:start position:0% +compensation recall the sort of +prolonged settling transient we saw when + + align:start position:0% +prolonged settling transient we saw when + + + align:start position:0% +prolonged settling transient we saw when +we applied small steps to the system we + + align:start position:0% +we applied small steps to the system we + + + align:start position:0% +we applied small steps to the system we +we can explain that as follows here's a + + align:start position:0% +we can explain that as follows here's a + + + align:start position:0% +we can explain that as follows here's a +root Locus diagram uh here we have + + align:start position:0% +root Locus diagram uh here we have + + + align:start position:0% +root Locus diagram uh here we have +assumed two low frequency poles uh + + align:start position:0% +assumed two low frequency poles uh + + + align:start position:0% +assumed two low frequency poles uh +they're not actually coincident as I've + + align:start position:0% +they're not actually coincident as I've + + + align:start position:0% +they're not actually coincident as I've +shown them but this models the uh + + align:start position:0% +shown them but this models the uh + + + align:start position:0% +shown them but this models the uh +two-pole rolloff that starts at low + + align:start position:0% +two-pole rolloff that starts at low + + + align:start position:0% +two-pole rolloff that starts at low +frequencies we have a zero which + + align:start position:0% +frequencies we have a zero which + + + align:start position:0% +frequencies we have a zero which +flattens out the curve to a 1/s roll off + + align:start position:0% +flattens out the curve to a 1/s roll off + + + align:start position:0% +flattens out the curve to a 1/s roll off +in the vicinity of + + align:start position:0% +in the vicinity of + + + align:start position:0% +in the vicinity of +crossover and then I've assumed some + + align:start position:0% +crossover and then I've assumed some + + + align:start position:0% +crossover and then I've assumed some +additional high frequency poles + + align:start position:0% +additional high frequency poles + + + align:start position:0% +additional high frequency poles +associated with the amplifier we've seen + + align:start position:0% +associated with the amplifier we've seen + + + align:start position:0% +associated with the amplifier we've seen +this kind of pattern before or we get a + + align:start position:0% +this kind of pattern before or we get a + + + align:start position:0% +this kind of pattern before or we get a +a root Locus picture that depending on + + align:start position:0% +a root Locus picture that depending on + + + align:start position:0% +a root Locus picture that depending on +the relative spacing of the poles in + + align:start position:0% +the relative spacing of the poles in + + + align:start position:0% +the relative spacing of the poles in +zero either circles around comes + + align:start position:0% +zero either circles around comes + + + align:start position:0% +zero either circles around comes +back one branch coming back to the zero + + align:start position:0% +back one branch coming back to the zero + + + align:start position:0% +back one branch coming back to the zero +another one going out here meeting an + + align:start position:0% +another one going out here meeting an + + + align:start position:0% +another one going out here meeting an +incoming branch and then finally + + align:start position:0% +incoming branch and then finally + + + align:start position:0% +incoming branch and then finally +breaking off like so or again for a + + align:start position:0% +breaking off like so or again for a + + + align:start position:0% +breaking off like so or again for a +different arrangement of the zero and + + align:start position:0% +different arrangement of the zero and + + + align:start position:0% +different arrangement of the zero and +poles uh does + + align:start position:0% +poles uh does + + + align:start position:0% +poles uh does +something like this we looked at this + + align:start position:0% +something like this we looked at this + + + align:start position:0% +something like this we looked at this +case in detail when we were when we + + align:start position:0% +case in detail when we were when we + + + align:start position:0% +case in detail when we were when we +first introduced the idea of root Locus + + align:start position:0% +first introduced the idea of root Locus + + + align:start position:0% +first introduced the idea of root Locus +in any case we normally operate this + + align:start position:0% +in any case we normally operate this + + + align:start position:0% +in any case we normally operate this +amplifier with its dominant closed loop + + align:start position:0% +amplifier with its dominant closed loop + + + align:start position:0% +amplifier with its dominant closed loop +Pooles out here somewhere and under + + align:start position:0% +Pooles out here somewhere and under + + + align:start position:0% +Pooles out here somewhere and under +those conditions the uh transient + + align:start position:0% +those conditions the uh transient + + + align:start position:0% +those conditions the uh transient +responses corresponding to the two + + align:start position:0% +responses corresponding to the two + + + align:start position:0% +responses corresponding to the two +amplifiers look pretty much the same + + align:start position:0% +amplifiers look pretty much the same + + + align:start position:0% +amplifiers look pretty much the same +because they're dominated by or the two + + align:start position:0% +because they're dominated by or the two + + + align:start position:0% +because they're dominated by or the two +possibilities look pretty much the same + + align:start position:0% +possibilities look pretty much the same + + + align:start position:0% +possibilities look pretty much the same +they're dominated by this closed loop + + align:start position:0% +they're dominated by this closed loop + + + align:start position:0% +they're dominated by this closed loop +pole pair + + align:start position:0% +pole pair + + + align:start position:0% +pole pair +however down in this region there's a + + align:start position:0% +however down in this region there's a + + + align:start position:0% +however down in this region there's a +pole zero doublet there's a zero + + align:start position:0% +pole zero doublet there's a zero + + + align:start position:0% +pole zero doublet there's a zero +associated with our + + align:start position:0% +associated with our + + + align:start position:0% +associated with our +compensation if you will the zero + + align:start position:0% +compensation if you will the zero + + + align:start position:0% +compensation if you will the zero +appears in the forward path the tal S + + align:start position:0% +appears in the forward path the tal S + + + align:start position:0% +appears in the forward path the tal S +Plus One expression in the forward path + + align:start position:0% +Plus One expression in the forward path + + + align:start position:0% +Plus One expression in the forward path +this Branch for the types of aot fots + + align:start position:0% +this Branch for the types of aot fots + + + align:start position:0% +this Branch for the types of aot fots +that we normally use has moved in quite + + align:start position:0% +that we normally use has moved in quite + + + align:start position:0% +that we normally use has moved in quite +close to the zero so we have a low + + align:start position:0% +close to the zero so we have a low + + + align:start position:0% +close to the zero so we have a low +frequency zero and at just a slightly + + align:start position:0% +frequency zero and at just a slightly + + + align:start position:0% +frequency zero and at just a slightly +higher frequency of pole they very + + align:start position:0% +higher frequency of pole they very + + + align:start position:0% +higher frequency of pole they very +nearly cancel they they're separated by + + align:start position:0% +nearly cancel they they're separated by + + + align:start position:0% +nearly cancel they they're separated by +a few percent uh the basic transient + + align:start position:0% +a few percent uh the basic transient + + + align:start position:0% +a few percent uh the basic transient +response is that associated with the + + align:start position:0% +response is that associated with the + + + align:start position:0% +response is that associated with the +complex conjugate pole pair + + align:start position:0% + + + + align:start position:0% + +but what we do is look if you will at + + align:start position:0% +but what we do is look if you will at + + + align:start position:0% +but what we do is look if you will at +the complex conjugate pole pair through + + align:start position:0% +the complex conjugate pole pair through + + + align:start position:0% +the complex conjugate pole pair through +a filter that has the following form + + align:start position:0% +a filter that has the following form + + + align:start position:0% +a filter that has the following form +here's the closely spaced dublet + + align:start position:0% +here's the closely spaced dublet + + + align:start position:0% +here's the closely spaced dublet +epsilon's a small number uh as the + + align:start position:0% +epsilon's a small number uh as the + + + align:start position:0% +epsilon's a small number uh as the +situation was shown in the view graph we + + align:start position:0% +situation was shown in the view graph we + + + align:start position:0% +situation was shown in the view graph we +have a zero at a somewhat lower + + align:start position:0% +have a zero at a somewhat lower + + + align:start position:0% +have a zero at a somewhat lower +frequency than the pole so we can + + align:start position:0% +frequency than the pole so we can + + + align:start position:0% +frequency than the pole so we can +visualize the system as as being one + + align:start position:0% +visualize the system as as being one + + + align:start position:0% +visualize the system as as being one +that gives us the step response + + align:start position:0% +that gives us the step response + + + align:start position:0% +that gives us the step response +corresponding to the two poles the + + align:start position:0% +corresponding to the two poles the + + + align:start position:0% +corresponding to the two poles the +dominant pole pair but we view that step + + align:start position:0% +dominant pole pair but we view that step + + + align:start position:0% +dominant pole pair but we view that step +response through a filter that has this + + align:start position:0% +response through a filter that has this + + + align:start position:0% +response through a filter that has this +transfer function well the step response + + align:start position:0% +transfer function well the step response + + + align:start position:0% +transfer function well the step response +of this transfer function is of the + + align:start position:0% +of this transfer function is of the + + + align:start position:0% +of this transfer function is of the +following form uh this is basically the + + align:start position:0% +following form uh this is basically the + + + align:start position:0% +following form uh this is basically the +uncompensated or the overcompensated + + align:start position:0% +uncompensated or the overcompensated + + + align:start position:0% +uncompensated or the overcompensated +scope probe if you adjust the transient + + align:start position:0% +scope probe if you adjust the transient + + + align:start position:0% +scope probe if you adjust the transient +response of a scope probe what you're + + align:start position:0% +response of a scope probe what you're + + + align:start position:0% +response of a scope probe what you're +really doing is trying to get a pole in + + align:start position:0% +really doing is trying to get a pole in + + + align:start position:0% +really doing is trying to get a pole in +a zero doublet to cancel each other uh + + align:start position:0% +a zero doublet to cancel each other uh + + + align:start position:0% +a zero doublet to cancel each other uh +so this is the case where we haven't + + align:start position:0% +so this is the case where we haven't + + + align:start position:0% +so this is the case where we haven't +perfectly compensated the scope probe + + align:start position:0% +perfectly compensated the scope probe + + + align:start position:0% +perfectly compensated the scope probe +this is the highpass version of the + + align:start position:0% +this is the highpass version of the + + + align:start position:0% +this is the highpass version of the +thing where the zero is located at a + + align:start position:0% +thing where the zero is located at a + + + align:start position:0% +thing where the zero is located at a +slightly lower frequency or a slightly + + align:start position:0% +slightly lower frequency or a slightly + + + align:start position:0% +slightly lower frequency or a slightly +longer time constant than the pole the + + align:start position:0% +longer time constant than the pole the + + + align:start position:0% +longer time constant than the pole the +step response of that sort of system uh + + align:start position:0% +step response of that sort of system uh + + + align:start position:0% +step response of that sort of system uh +is as follows if we put in a unit step + + align:start position:0% +is as follows if we put in a unit step + + + align:start position:0% +is as follows if we put in a unit step +we get a in this case with a zero at + + align:start position:0% +we get a in this case with a zero at + + + align:start position:0% +we get a in this case with a zero at +lower frequency we get an output that + + align:start position:0% +lower frequency we get an output that + + + align:start position:0% +lower frequency we get an output that +overshoots final value by an amount + + align:start position:0% +overshoots final value by an amount + + + align:start position:0% +overshoots final value by an amount +Epsilon decays with a time constant + + align:start position:0% +Epsilon decays with a time constant + + + align:start position:0% +Epsilon decays with a time constant +corresponding to the pole location in + + align:start position:0% +corresponding to the pole location in + + + align:start position:0% +corresponding to the pole location in +our particular case the pole is located + + align:start position:0% +our particular case the pole is located + + + align:start position:0% +our particular case the pole is located +at a considerably lower frequency than + + align:start position:0% +at a considerably lower frequency than + + + align:start position:0% +at a considerably lower frequency than +the dominant response associated with + + align:start position:0% +the dominant response associated with + + + align:start position:0% +the dominant response associated with +the dominant pole pair and so what we + + align:start position:0% +the dominant pole pair and so what we + + + align:start position:0% +the dominant pole pair and so what we +see is the highfrequency + + align:start position:0% +see is the highfrequency + + + align:start position:0% +see is the highfrequency +response the overshoot if you will as + + align:start position:0% +response the overshoot if you will as + + + align:start position:0% +response the overshoot if you will as +the dominant response but there's a long + + align:start position:0% +the dominant response but there's a long + + + align:start position:0% +the dominant response but there's a long +tail that reflects the much longer time + + align:start position:0% +tail that reflects the much longer time + + + align:start position:0% +tail that reflects the much longer time +constant associated with the pole of the + + align:start position:0% +constant associated with the pole of the + + + align:start position:0% +constant associated with the pole of the +pole zero doublet and that sort of thing + + align:start position:0% +pole zero doublet and that sort of thing + + + align:start position:0% +pole zero doublet and that sort of thing +happens as I say with lag compensation + + align:start position:0% +happens as I say with lag compensation + + + align:start position:0% +happens as I say with lag compensation +as well as as with + + align:start position:0% +as well as as with + + + align:start position:0% +as well as as with +two- pole compensation when we do + + align:start position:0% +two- pole compensation when we do + + + align:start position:0% +two- pole compensation when we do +feedback compensation and so one of the + + align:start position:0% +feedback compensation and so one of the + + + align:start position:0% +feedback compensation and so one of the +disadvantages of this sort of + + align:start position:0% +disadvantages of this sort of + + + align:start position:0% +disadvantages of this sort of +compensation uh may be that if we if we + + align:start position:0% +compensation uh may be that if we if we + + + align:start position:0% +compensation uh may be that if we if we +are really concerned about settling to a + + align:start position:0% +are really concerned about settling to a + + + align:start position:0% +are really concerned about settling to a +very small fraction of final value that + + align:start position:0% +very small fraction of final value that + + + align:start position:0% +very small fraction of final value that +settling time may be + + align:start position:0% +settling time may be + + + align:start position:0% +settling time may be +compromised next time we'll look at two + + align:start position:0% +compromised next time we'll look at two + + + align:start position:0% +compromised next time we'll look at two +other ways that we can use monor Loop + + align:start position:0% +other ways that we can use monor Loop + + + align:start position:0% +other ways that we can use monor Loop +compensation for specific applications + + align:start position:0% +compensation for specific applications + + + align:start position:0% +compensation for specific applications +to improve the performance of this type + + align:start position:0% +to improve the performance of this type + + + align:start position:0% +to improve the performance of this type +of operational amplifier thank + + align:start position:0% +of operational amplifier thank + + + align:start position:0% +of operational amplifier thank +you \ No newline at end of file