% Claudio Talarico:
% common emitter amplifier (small signal T-model)
% bjtampl.m

clc; clear all; close all;
syms v1 v2 i1 i2 iB;
syms RS RB rE beta RL;

eqns = [v1 == RS*i1 + RB*i2; ...
    RB*i2 == rE*(beta+1)*iB; ...
    i1 == i2 + iB];
sol = solve(eqns, i1, i2, iB);
iB = sol.iB;
v2 = RL*beta*iB;
Av = v2/v1;
fprintf('Av = \n');
pretty(Av)
fprintf('\n');