Analog Circuits and Systems 1 Prof. K Radhakrishna Rao...

Analog Circuits and Systems 1 Prof. K Radhakrishna Rao

Indian Institute of Science – Bangalore

Module No # 08Lecture No # 38

Design of PLL And FLL

Today we are having the thirty eighth lecture. The last class we had started with discussion about

phase locked loop which is strictly speaking a frequency lock loop and discussed some of the

applications at the end. Today we will go into further details about the sign of this so called Pll or

Fll.

(Refer Slide Time: 0:56)

So we had seen that frequency follower is a phase follower. We had actually earlier the true VLL

having a VCP that was getting replaced by an VCO which is an independent oscillator controlled

by a control voltage in the loop itself. So the Omega I is good and we consider this in terms of

initially. This signal is not applied as having a VCQ here which corresponds to an Omega not Q

here and this reconnected.

Again this PLL has now a free running frequency this is called the free running frequency which

can be set by adjusting the VCO parameters. So that changes both KVCO which is called the

sensitivity of the VCO K which is nothing but Delta Omega not by Delta VC. So the VCQ makes

this free run Omega naught Q and nothing comes out of this low pass filter if there is V 2. So

output remains continuous to remain VCQ and at each point.

If one now phase, we put here corresponding to Omega I equal to Omega naught Q. Again

nothing should happen, however this has component of twice Omega naught Q at that point and

DC component. So the DC component corresponds to Cos Phi because there is likely to be phase

shift by Phi between this component and this component. So that component was Phi should be

also going to 0.

So that these remain at VCQ and therefore the phase shift that I suggested automatically to Pi by

two. So Phi becomes equal to Pi by 2 for this, so it is now phase locked to Pi by two. So a phase

follower, frequency follower is naturally a phase follower. The phase detector does know

whether it is the frequency that is varying or the phase that is changing. So it just follow the

phase Delta Phi not by Delta Phi I.

Therefore is equal to 1 /1 + 1 over loop gain and is made up of this components that is DC

components, it is KPD then KA and KVC that is what is called DC loop gain and then it has the

component here corresponding to low pass filter. So the actual loop gain is nothing but GLO

which is KPD KC VCO K divided by this transfer function one plus S by Omega LP where

Omega LP is equal to one by RC.

So if you substitute this by one over GL here. We get S by GL naught + S square by GL naught

Omega LP. So this is what is called the natural frequency square of the system and this is what is

called Omega N into Q okay and therefore the Omega N into Q will be equated to GL. So we

have the Q = route of GL not by Omega LP for this Omega N being = square root of GL not into

Omega LP.

So these are the equations governing the phase following action Delta Phi not by Delta Phi I

strictly should be = 1. If these components do not contribute much that means actually S = J

Omega here actually corresponds to the dynamics of the phase Log. The static characteristics just

say output phase follows the input phase, output frequency is equal to input frequency. That

means if S = J omega substitute in this.

What does omega corresponds to omega, corresponds to the rate of change of frequency of the

change in frequency. So frequency of the change in frequency is the same as frequency of the

change in phase. So it is that Omega that is to be put here. So this is something that we shall

strictly understand very well. So once the phase locking phenomenon is understood as a linear

system like this S equal to J Omega corresponds to the frequency of the change in frequency.


Lock range of the system is actually static characteristic, where we had changed the Omega

incoming starting from Omega naught Q and if we plot VC it will be initially at VCQ at this

point corresponding to Omega naught Q. There after it is going to change on either side keep on

changing. So the VCQ is going to change from is equal to VC corresponding value depending

upon, how far away from Omega not Q Omega I and at one point of time it goes out of line

again.

We start with Omega = Omega naught Q go towards this range and stops at 2, this point and

come backs to the free line frequency. So this range where it goes out of lock on either side of

Omega naught Q is called the lock range and that lock range is governed by the fact that the

phase shift is starts with Pi by 2. Here it goes on all the way up to, let us say 0 on one side and Pi

on the other side.

So that is the lock range 0 to Pi around Pi by 2 is the lock range and there after it goes out of

lock. If the condition is that the amplifier does not go to saturation and the VCO should function

in the this range. The satisfactory as a linear VCO. So that is the static characteristic of the PLL

and again if we now do not start with Omega = 0 and go on either side. But start with Omega I at

the low frequency end or high frequency end.

Then we had mention that Omega I - Omega naught Q itself is a component which is much

greater than Omega LP. So nothing happens at the output of the low pass filter, nothing comes

out. So therefore, there is no locking taking place. So when you come this way, if this is Omega I

= Omega naught Q, one has to come pretty close to Omega not Q in order to get into the locking

mechanism.

So it just has to come pretty close from here all the way up to this and then it gets locked and it

follows. This flow which is nothing, but Omega I - Omega not Q divided by KVC. So this is one

over KVCO it can go on all the way up to this come down. So on this side it can go up to the

lock range. So this is the lock range, this is called the capture range. Same things happens when

Omega naught Q - Omega I.

This is what happens when Omega I - Omega naught, this is what happens in Omega naught Q -

Omega I is much greater than Omega LP on the other side Omega I - Omega naught Q much

greater than Omega LP. What happens is the other one comes like this gets structure and goes on

like this all the way upto this and goes out of lock on this side.

So this range is the capture range and always less than the lock range it can be controlled by the

low pass filter and we had seen how capture range can be roughly gone in terms of the equation

which is Delta Omega C = Delta Omega l by square root of 1 + Delta Omega C by Omega LP

equals square. So this is approximated under this situation Delta Omega C by Omega LP is much

greater than 1. If one can be neglected and captured in the square root of lock range into Omega

l. So otherwise you have to solve this quadratic equation to get the capture range next.


We have designed PLL and simulated is lock range, capture range and its characteristics and used

it for FM detection. So let us see how it can be understood the PLL designed has a VCO with

sensitivity equal to Hundred hertz per volt around a quiescent frequency of Thousand just for the

amplitude of the output square wave, sine wave it can be either square wave or sine wave.

Accordingly the lock range will change VCO is, if it is a square wave or sine wave the VCO

output is taken to be 10 volts. The inputs to the PLL is a square wave or sine wave of amplitude 5

volts. We will do it for both types of wave forms. The phase detector is a multiplier VX VY by

10 followed by a low pass filter R = 1 K and C = 1 micro fahrenheit. This is the complete PLL

circuit.


So we have fixed all the parameters of the PLL GLO is nothing but that is DC loop gain is

KVCO KPD KA here. We have not put an amplifier, so the K is 1. So low pass filter output is

directly connected to the VCO. So K = 1, this = 1 and KVCO. We have taken Hundred hours per

volt KPD is nothing. But it is VP that is V average in the case of an multiplier and low pass filter

V average was VP VP dash VP is the input peak.

Sine wave peak of the Sine wave VP dash is the output of the VCO. VP VP dash by 20 Cos Phi.

So Delta V average by Delta Phi is the K PD. So that KPD is- VPVP dash by 20 Sine Phi. So we

are investigating at Omega = Omega naught Q to start with, so Phi is Pi by 2. So at that Sin Pi by

2 is that particular thing is Delta V average Sin Pi by 2 is 0.

Therefore this value of V average is going to be 0 there is Sin Pi by 2 is 1 and Cos Pi is 0. So the

value of average is 0 and Sine Phi is 1 and therefore this is - VP VP dash by 20. In our case this

VP being 5 volts K into VP dash being 10 volts by 20 is 2.5 volts per radians. So these values is

substituted, we have here - 200 Pi into 2.5 = - 500 Pi.

It is indicating that is negative feedback. So GLO into Pi by two is the lock range which is 500 Pi

into Pi by 2 which is roughly 2500 radians per second + 3 Three 93 around 1000 hertz which is

going to give you a lock range of 1300 and 93 hertz to 600 and 7 hertz. So this is the case only if

the loop gain is maintained very large in the range.

Then the error is going to be very small and therefore it is going to be within this range in

common practice. Because if it is sin five the characteristic instead of linear phase detection at

linear phase detection we have seen will be just the Sine wave converted to, then apply to the

multiplier then this value of KPD is maintained throughout the range. However if it is just a time

wave, that is the average is the Cos wave and this is a sine wave.

So that is the form for the phase detection. So that is the Sine wave, so this particular thing is

going to be the case only around this region of operation very small region. We can take for

granted that KPD is constant as it near 0 or Pi it goes towards 0. So most of the time the lock

range is completed with this value it is valid only for short range. So it is much less than this as

far as the phase detector which is non-linear is concerned with the linear phase detector it can be

almost reached fully.


If we now substitute for the capture range is nothing but the lock range is divided. By this we get

this and by solving this equation one obtains capture range nearly equal to 1200 radians per

second and Delta Phi not by Delta Phi I is Omega not by Omega I / 1 + S by GLO which is 500

Pi S square by GL naught Omega LP which his 500 Pi into 1000 radians per second.

So Omega N of this term it has been now designed comes out to be 1400 and 14 radians per

second and Q is 1.414. Let us look at this system as a sum of low pass filter it is a characteristic

as the low pass filter. So as far as S is concerned it is defining the dynamics of the system that is,

I must now add for example step input in phase or a step change in frequency that is a frequency

is state change suddenly from one values another at the input.

So this is Omega I initial which Omega I equal to Omega naught Q to Omega I which is different

from Omega naught Q. So that is the step changing frequency it is equivalent to finding the step

response. So what should happen is, if you see the control voltage it will have to change

suddenly from this Q to any value of VC as a step strictly. But because of this nature it is going

to be changing in this manner. So this is the process of capture of one frequency starting from

another frequency.

This is the step changing frequency and this should be the characteristic if it is a second order

and the number of such peaks can be counted give the value of Q ringing frequency corresponds

to a close thing for Omega N. Strictly speaking it is Omega N the square root of 1-1 by 2 Q

square. We had already understood, when we discussed passive Network and low pass filters

second order same characteristic exists for the PLL also. So let us look at that so I have just

apply the step.


So the frequency in the input as it changed suddenly from one value to another. So what happens

here is the VC value is going to change at the input of them VCO from one value to another. So

this is the way and you can see this particular thing peaking like this is nothing but the Ripple

which is still unfiltered. This corresponds to Two Omega I component, so that unfiltered two

Omega I component still exists.

But the DC component you can stays here is something that is well understood in terms of the

filter function. Now it is applicable equally well in the case of the PLL. So this is called the step

response of the PLL that is step change in frequency at the input of the PLL and this change that

is clearly observed at the input of the VCO of the PLL.


So when the input is a square wave of 5 volt amplitude and VCO output is a square wave of 10

volt amplitude. The only difference is KPD into Pi by 2 which has to be recalculated till now.

Because it is a linear phase detector, so KPD into Pi by 2. This case is nothing but 5 into 5. This

10 volts is the VCO output 5 volts is the input to the PLL square wave Input and this is

corresponding to the multiplier voltage Ten volts reference voltage.

So this is KPD Pi by 2 that is because we had seen that earlier once he realize the T phase. This

corresponds to slope corresponds to KPD at KPD into Pi. This Pi by 2 is the peak change on DC

voltage on either side of VCQ. So this is nothing but KPD into Pi by 2, so that is the maximum

change on the sea on either side of VCQ and therefore Omega naught Q should be capable of

changing by this into KVCO.

So KPD into Pi by 2 into KVCO K being 1 is the lock range 500 hertz. KVCO is 100 hertz, so

that multiplied by 5 volts. So this is 5 times 100 which is 500 Hertz around thousand. We can see

this


So this is the VCO output volts + - 10 volts and PLL input is + - 5 volts square wave and what

has been done is that the alignment of another VCO the input of the VLL to which I am applying

identical VCO at input. So here the same VCO has put and I am applying a VC at that point to

change the incoming frequency. So at that point I am applying a voltage of VC equal to four

volts to that VCO which is heading toward and then what happens?

Show the alignment please understand it this way we have a VCO here and this is VC. So this is

equal to change in frequency from Omega naught Q to Omega naught Q which is + 4 times a 100

which is 400. So 1400 corresponds to the input frequency on VC = 4 volts. So this is what is

happening to the PLL and this same VCO is put in feedback path.

So that is the Macro moral that we had used and we have the low pass filter 1 K micro fare

which is getting connected to the VCO input. So at this point immediately the output frequency

should correspond to 1400 and this should change from the coincidence to 4 volts. So initial

consent is 0 to 4 volts. So that is what has happened the phase change has nearly 0. You can see

the output and input they are almost in phase.

So this has come close to the lock range of this side okay now the same thing is repeated with

VC = - 3 volt that means it has been changed it to 700 hertz as the input and then the phase shift

goes close to you can see 180 Degrees. So phase shift is going close to 180 Degrees phase shift is

going close to 0. So we have almost covered the lock range, this way and thereafter it is going to

all the block.

It is primarily due to the fact that the double frequency component is still not eliminated. So the

voltage is still around so called Three volts. So it is going all the way up 5 volts and therefore it

is going out of Lock this is happening more at the lower frequency end. Then at higher frequency

because at higher frequency low pass filter is better. So you can see the 2 Omega component is

smaller in amplitude where us at low frequency 2 Omega component is larger in amplitude.

So that is restricting the lock range to something close to Seven Hundred hertz on this side and

closed 1400. What is on the other side? So this unfiltered triple is responsible for restricting the

lock range because once it goes out of lock recaptured. So that means you have to come closer.

So that means this, some system dynamics is not functioning properly. So it is better to in lock

range as long as you want track the change in phase change in frequency that is happening at the

input to be followed at the output.

So these are the points that must be born in mind while designing the system. Range has been

constraint even though it is a linear phase detector to value which is less than what is predicted.

Because the actual predicted lock range is Five Hundred hertz on the lower side and all the way

up to Thousand Five Hundred on the other side. So it is rejected by the Rebel that has not yet

completely removed by the low pass filter.


So this is the dynamics of the phase lock as an FM detector or FS case detection in there

dynamic characteristics of the phase lock tested. In fact if input frequency of phase lock

remaining constant at a value it is stating in steps lately then what it means that you are testing

the static characteristics of the PLL. It is only when the frequency of the input is changing at a

frequency, it is that frequency that comes as S = G Omega.

Then only the Dynamics of the phase lock group is getting distant so that is why in order to test

the Dynamics of this log group the actual input that must be applied is a FM or FSK. So that is

what is done, we have put the same VCO at the input of the PLL as that is there in the loop and

we have made the quiescent frequency of this loop is GLO as same as that means, this is the

transfer filter which is received modulating frequency and transmitting the career here and then

through the media it is received by the receiving antenna.

And accepted by the PLL which is tuned to the same carrier frequency 100 hertz as that of the

transmitted frequency. So the frequency deviation is controlled by this control voltage VC. So if

you apply a DC here that is a fixed frequency if you apply AC at certain frequency Omega M.

Then this VC is replaced by VP Sin Omega M T that means this becomes frequency deviation.

What is frequency deviation ?

100 times VP in this case, so the frequency deviation can be controlled it is going to test the

dynamic range. The frequency deviation can be as much as the lock range if only this phase lock

is tuned then the quiescent frequency phase lock group corresponds to the career then the full

dynamic range of the PLL is exploited. So the phase can change from Pi / 2 quiscent to Pi on the

side and 0 on the other side.

So that is important to understand it is the rate at which it changes depends upon the modulating

frequency of Omega M. So we have several components to be thought of there is this career here

+ Delta Omega D Sin Omega MT. This is the FM case produced here the career here corresponds

to, let us say 1000 and 100 times VC here.

This is the frequency deviation DC and this is the modulating frequency. So there are three

frequency component in the incoming frequency component of an FM career corresponds to the

quiscent voltage of a voltage follower and this corresponds to the input slightly applied for the

voltage follower in the case of frequency follower.

This is the amplitude of change of frequency, this is the rate of change of frequency Omega M.

So what should happen is the output frequency is same as input that way if this is an FM, same

FM is reproduced here. Delta Omega D Sine Omega M T if that means this is one there is Delta

Phi not Delta Phi is exactly = 1 this FM which is reproduced is the same as that fm that is

coming except that if Omega not q the same as career.

This will be let us say Sine of this and this will be Cosine there will be Ninety degree phase

between the Sine and this Cosine is that point clear that has given and change in frequency will

be followed exactly. However is Omega M that is the frequency that test the Dynamics of the

phase lock when that is increased and this is increased does change in frequency will not be same

or the frequency deviation P is around the quiscent will not be the same.

But we can actually be more then that is the danger because if it is more deviating they may call

or lock range and the system again becomes no use for linear analysis. So it has to get captured

and come back to the operator. So this is the danger that means the rate with which the frequency

is changed here in the FM should be much less than the nature of the frequency of the system. So

it is not the thought output is not okay.

So if you apply extra frequency again the Dynamics gets tested because it will start ringing at the

natural frequency of the system, that we have already shown here. So this is the natural

frequency where is this trying to peak now. Omega M has to be kept less than the natural

frequency of this establishment. So this is how to ordered be free from this, so this is what is

done this is now for the FM detected output.

So because it is reproducing the modulating frequency just component point exactly in the same

fashion. So if One volt changes the peak here that same one volt change should be there if only

Omega M is much lesser than the frequency.


So it is done here this is getting more related by Sine wave, you can see that this frequency is

changing okay at a certain rate and it is frequency modulated it can change see this phase shift is

changing at times it is coming close to 0 at times it is going close to Pi by Pi and then it crosses

through Pi / 2. So phase is changing continuously does the modulating frequency and you can

see the FM detected by form initially it is not tracking.

Once the lock takes place it is going on tracking the change in frequency faithfully in the same

magnitude of course, you have that two Omega component then Triple still unfiltered if one

wants, one can put air filter with a buffer and the filter outside the loop buffer is necessary

otherwise it will interact with the loop dynamics and it no use of changing second order filter.

Because it will make the system become more stable the whole system becomes third order and

becomes unstable. So one has to put another filter on better filters outside the loop to remove the

Omega component completely. So here VP has been destructed to one volt in the same one volt

is detected at same frequency of 100 Hertz modulating frequency show 100 hertz is the career

100 hertz is the FM VP of that FM in a modulating frequency is one volt. So that it is well within

the lock range by so VPC the carrier is 5 volts till same as before VPCO are the VCO is 10 volts.

These are all sine waves.


So now FSK detection it is square wave input. You can see the blue line, the square wave + - 1

volt FM is 2.5 Hertz it is still reduced. So that the rise time and fall time of the square wave is

reproduced faithfully by the FM detector. So this is still lower earlier we have taken 100 Hertz at

the modulating Sine wave frequency here we have gone for 2.5 Hertz as the frequency of FSK.

So the frequency is changed in steps. So you have + 1 taking into towards 0 and - 1 taking it

towards Pi for around Pi by 2 the quiescent. So VPC is still 5 volts career amplitude PCO is 10

volts. So that is maintained and you can see clearly the process of capture and it takes certain

capture time in as stated earlier. All the capture time going to be depended also on the low pass

filter in the Dynamics.

But it depends upon the whole transfer as one by 1 + S by Omega naught Q + S square / Omega

naught square and K being 1.414. You can see just one peak here. We had seen earlier also at

least, we remember us so this is what you seen the same thing is repeated here in FSK. So this is

the reproduction of the pulse the information that is modulating the career. This is the FM

detected output, this is the Omega component heading over this.


We come to the other important application frequency translation which has been earlier

discussed. However now we are simulating this using an example. Omega I is the input, Omega

naught is the output. So here we get Omega I - omega naught and omega I + omega naught being

very high this is eliminated by the low pass filter and it response Omega I - omega naught which

is low frequency count and then there is a shift of the Delta Omega.

Therefore here we cannot decide that Delta Omega + Omega I - Omega naught is lower or Delta

Omega - Omega I - Omega naught is the lower frequency count component can be one of these

depending upon weather we want Omega naught to be higher or lower than the Omega I. So

assuming that is either this or this we get and output frequency which is Omega I - Delta Omega

naught or Omega naught = Omega I + Omega Delta Omega. So how this is done properly, this is

illustrated by an example again.


So here we have chosen 1100 hertz to be derived from 1000 hertz an 100 hertz. So now we want

to select 1000 + 100 and naught 1000 -100. So FI = 1000 hertz VP = 5 volts Delta F is 100 hertz

shift which is applied at the other input VP = 10 volts. So now what happens if we have tuned

this properly. So this is the low pass filter output and this is the unfiltered component at the filter.

(Refer Slide time: 47:20)

So one can see that the frequency now selected is 1100 hertz how do you select it that means this

particular VCO will have to have the what is that the Omega naught Q that is free running

frequency properly selected in order to select the right component Omega naught Q has to be

pretty close to be frequency that we are wanting to select. So the best way is when it is FSK

detection, when it is 1100.

We want to select, we better make the other one that we want to reject this none 100 hertz. We

better make our VC Omega naught Q = 1100 that was the best way. So if Omega naught Q is

made = 1100 or above 100 maybe 1000. Let us say 200 as usual and as long as we show that lock

range is pretty high.

We can go from anywhere from this to this as the free running frequency of the VCO that is

incorporated in this of the consideration loop of frequency translation. So when that is done we

automatically pick the 1100 Hertz which you can see here emerges as the output, this is the input

frequency, blue is the input frequency which is 1000 hertz and this is 1100 Hertz that has been

selected by the loop another example FI is 1000 hertz.


So we want to derive 100 hertz from 1000 hertz using 1000 hertz as one input and 900 hertz as

the other input that means 1000 - 900 is what is to be selected not 1000 + 100. So that means it is

easy now to make the variant frequency of VCO close to Hundred hertz within the lock range of

the VCO PLL that is formed using the two multipliers.

So once the VCO is close to 100 hertz receiving equal 100 Hertz immediately one can say that it

is getting locked. You can be sure that it is getting locked because the Dynamics is reproduced

hear that peak of one still existing. So it starts and gets locked and then you can see the output is

the 100 hertz that is selected when 1000 hertz is one input and the Hertz is the other input that is

frequency translation for you.

So this is an important loop in frequency translation apart from multiplication. So that is very

simple you both fake the VCO to act VCO with a counter which will countdown, So that it is

dividing by N. So divide by N that we have illustrated in the last class and you can get a

frequency multiplication by N divided by M that way suitable frequency calculation input a

powerful tool for exact frequency synthesis.


Speed control of Motors, nothing but again reproduction of the DLL in terms of electrical

components. So the power drive here running a motor with what I called Optical generator is

nothing, but the shaft connected with disk with slit in the circumference opto coupler which will

convert the whole thing into rotation as in the phase of pulses here. So Omega naught output of

the oscillator here which is an electrical oscillator is 2 Pi into N is the RPM of the motor that by

60 patients revolution per second.

Number of pulses output in seconds which is N number of slits. So every revolution produces N

pulses. So it is a Pulse generator that with this frequency, so this is the same phase detector loop

filter may not be necessary. Because the power drive itself is the motor act as a low pass filter. So

this is the split control of motors AM detection AM comes from the let us say, antenna and goes

through limiter.

So that the AM is removed here, so only the career is selected here. So several career might just

appear here. So this has to be frequency-selective, now that means this is one or maybe because

both FM detection and AM detection. This PLL act as a frequency and select the career that is

corresponding to Omega naught Q. So if you want or certain career to be selected it is necessary

to tune it this Omega naught Q and you select the career that you want to select.

At this point as Omega naught Q, now this career is reproduced here. But only with a phase shift

of 90 degrees that if this is Sine omega, this will be Cos Omega. So if you multiply Omega CT

AM corresponding to that career, we will still not get any output because of the phase shift of Pi

by 2. So there is a phase shift of which is preferably Pi by 2, let us see so that this becomes the

same career in phase as the input career that is selected.

So when you multiply it by that Cos Sine. This is Sine which is also become Sine you will get

again when you multiply Sine Square Omega C and therefore there will be the double the carrier

at this point and the modulated output or modulating frequency that is here. So that is detected at

this point.

So this is the frequency selective or synchronous cell detection the carrier is generated by the

PLL that is all that happens. So that requires this kind of arrangement after that it is nothing but

synchronous detection because you are able to generate the career, that is carried information at

the receiving end.


That is so we have modulated the career amplitude, modulated the career just by using a

multiplier input. So this is also going to generate using a multiplier here and multiplying the

career. The modulating frequency, the career has to have the modulating frequency has to have a

DC. So if you enter where AM is generated, this is the AM generator. So one has let us say, a DC

+ VP Sine Omega not and this is the VPC sine omega CT.

So at the output when you multiply you can get the carrier + 3 component corresponding to

Omega C + Omega M and Omega C - Omega M. So this therefore is nothing but a as long as the

amplitude of VDC is greater than VP it is going to be M giving you AM at the output of this that

AM is supplied here and then that is what is detecting. So that AM comes there and it is going to

leave it and apply to the PLL and this is the output of the PLL just simply generates only with the

carrier.


So this career is being used after phase shift by 90 degree to multiply with the AM at the

receiving antenna. So what happens is this is the AM that is modulating frequency of the AM and

this is the detected AM. This is AM detection


So IC PLL are popularized 1 are 561560 CD 4046 KVCO sensitivity of one of the most popular

PLL IM 565 national semiconductor KVCO is 10 kilo hertz = F naught = 10 kilohertz. The 6600

hertz per volt, so 6.6 kilohertz per volt phase detector sensitivity is .38 volts per radiance VCO

maximum operating frequency is about 500 kilohertz.

So this is a typical IC PLL that is available, so we have treated PLL as control system with the

same kind of activity as a system or any system or voltage regulator. So all this control system

have the same dynamics to be understood, no complicated issues involved. Because it is a phase

lock loop, it is same as of Voltage follower or Current follower or a phase follower or frequency

follower always have the same dynamics of operation and same ideas of frequency

compensation. that we have adopted for this system design. Thank you very much

Analog Circuits and Systems 1 Prof. K Radhakrishna Rao...

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