The objective of this project is to design a multi-pole amplifier and to analyze

Question

The objective of this project is to design a multi-pole amplifier and to analyze it using PSpice. The purpose is to observe the instability of the amplifier, and then examine its behavior when feedback is added and when a dominant pole compensation stage is incorporated into the circuit in order to correct for its instability. Project Description A 3-pole amplifier is to have the following characteristics: Poles at f_2 = 100 kHz, f_2 = 600kHz, f_3 =600 kHz Open-circuit voltage gain A_e = 20,000 Input resistance R_ea = 10 k Ohm Output resistance R_e = 30 Ohm Load resistance R_e = 12 k Ohm All resistors in all three stages of the amplifier are to be 10 k Ohm It is assumed that the feedback is a series voltage type with gaina1000. Build and test the circuit without the feedback in place. Using PSpice, obtain Bode Plots for the gain Magnitude and Phase of the open-loop amplifier. Determine the Gain Margin (GM), the Phase Margin (PM), and the corresponding frequencies farm and fine. Also, determine and show a plot of the transient response for the output voltage across Ri. Give your comments. Add a compensation stage (a pole at f_c) to the open loop circuit, so that the phase margin is 45, assuming that beta = 0.001 Using PSpice, obtain Bode Plots (Magnitude and Phase)of the compensated amplifier. Determine the Gain Margin (GM), the Phase Margin (PM), and the corresponding frequencies few and fine. Also, determine and show a plot of the transient response for the output voltage across Give your comments. Build and test the circuit with the feedback added to the open-loop with compensation circuit. Using PSpice, obtain Bode Plots (Magnitude and Phase)of the closed-loop amplifier. Determine the Gain Margin (GM) the Phase Margin (PM), and the corresponding frequencies f_GM and f_FM. Also, determine and show a plot of the transient response for the output voltage across R_t. Give your comments. Among the issues that you see relevant, comment on things such as stability, effect(s) of pole compensation, effect of feedback on gain, etc. Hasthe latter achieved its purpose? Why? Why not? Deliverables Analyze all three circuits (open-loop, open loop with compensation, and closed-loop) theoretically Build all three circuits using PSpice/OrCAD.

Explanation / Answer

2.)

% this is a comment

% parameters

R= 4;

L = 1.330 e-3;

Rind = 100 e-3;

C = 94 e-6;

Resr = 10 e-3

Vs = 42;

Va = 12;

D=Va/Vs;

Kd= Vs/(1-D)^2;

Sz1=1/(Resr*C);

Req = R-(Resr*R/(Resr+R));

Sz2 = (1/L)*(1-D)^2* Req – Rind/L;

Re=(Resr*R)/( Resr+R);

Wo = (1/sqrt(L*C)) * sqrt((Rind+re*D*(1-D))/(Resr+R));

Q = Wo/(((Rind+re*(1-D))/L)+(1/(C*(Resr+R))));

% polynomials are entered in descending order of S.

n1=[1/Sz1 1]

n2=[-1/Sz2 1]

NUM=conv(n1,n2)

% the convolution realizes the product of 2 polynomials

% define denumerator

DEN = [1/(Wo^2) 1/(Wo*Q) 1]

% create TF variable

sysTF = Kd * tf(NUM,DEN)

which returns

Transfer function.

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