فیدبک موازی-سری(ولتاژ-ولتاژ)

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% Three-stage amplifier

% First stage: common emitter
% Second stage: common emitter
% Third stage: common collector
clc
clear
close all

% Parameters
Ic1 = 0.5e-3;
Ic2 = 1e-3;
Ic3 = 5e-3;
hfe = 100;
hfe1 = 100;
hfe2 = 100;
hfe3 = 100;
rpi = inf;
ro = inf;
Rs = 150;
RE = 100;
R1 = 9e3;
R2 = 5e3;
RL = 100;
RF = 650;
VT=25.8e-3;

% First stage
gm1 = Ic1 / VT;
rpi1 = hfe1 / gm1;
ro1 = inf;
re1= VT/Ic1;
%gain
ZB1= (1+hfe)*((86.67)+re1); %RE || RF=100 || 650=86.67
Av1= -(2.02e3)/(86.67+re1); %R1 || ZB2=9e3 || 2.605e3=2.02e3

% Second stage
gm2 = Ic2 / VT;
rpi2 = hfe2 / gm2;
ro2 = inf;
re2= VT/Ic2;
%gain
ZB2=(1+hfe)*re2;
Av2 = -gm2 * 3.27e3;%R2 || ZB3=5e3 || 9.433e3=3.27e3

% Third stage
gm3 = Ic3 / VT;
rpi3 = hfe3 / gm3;
ro3 = inf;
re3= VT/Ic3;
%gain
ZB3=(1+hfe)*(88.24+re3);%RL || (RE + RF)=100 || 750=88.24
Av3=88.24/(88.24+re3);

%Power supply impedace
ZP=ZB1/(ZB1+Rs);

% Total gain

Av_total = Av1 * Av2 * Av3;

disp(['Total gain: ', num2str(Av_total)]);

A=(Av_total*ZB1)/(Rs+ZB1);%amplifier gain without feedback
B=(RE)/(RE+RF);%feedback coefficient

% Feedback input resistance
Ri=ZB1+Rs;
Rif= Ri*(1+A*B);

disp(['Feedback input resistance: ', num2str(Rif)]);

% Feedback output resistance
Ro=33.74; %XB3=R2=5e3 , [(XB3/(1+hfe))+re3]=[(5e3/(1+100))+re3]=54.5 , 54.5 || 100 || 750=33.74

Rof=Ro/(1+A*B);

disp(['Feedback output resistance: ', num2str(Rof)]);

% Overall voltage gain with feedback
Af= A/(1+A*B);

disp(['Overall voltage gain with feedback: ', num2str(Af)]);

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فیدبک سری-موازی(جریان-جریان)

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% Two-stage amplifier

% First stage: common emitter
% Second stage: common emitter

clc
clear
close all

% Parameters
Ic1 = 2.5e-3;
Ic2 = 5e-3;
hfe = 100;
VT=25e-3;

re1=VT/Ic1;
rpi1=hfe*re1;
re2=VT/Ic2;
rpi2=hfe*re2;

Rs = 2e3;
RC1 = 10e3;
RC2 = 6.3e3;
RE2 = 0.1e3;
RF = 1.9e3;

If=-0.1;
Io=2;

A=(-0.5e3/6.3e3)*31500;%(Ri/RC2)*Vo/Vb1
B=If/Io;

% Feedback input resistance
Ri=0.5e3; %2e3 || 2e3 || 1e3
ZB1=hfe*re1;
Rif= Ri/(1+A*B);

disp(['Feedback input resistance: ', num2str(Rif)]);

% Feedback output resistance
Ro=95+5+100; %(1.9e3 || 0.1e3)+re2+10e3 || ro1/1+hfe -->ro=inf

Rof=Ro*(1+A*B);

disp(['Feedback output resistance: ', num2str(Rof)]);

% Voltage gain
Av=(-6.3e3/2e3)*(-19.85);%(-Ic2/Rs)*Af

disp(['Voltage gain: ', num2str(Av)]);

% Overall voltage gain with feedback
Af= A/(1+A*B);

disp(['Overall voltage gain with feedback: ', num2str(Af)]);