modeling of transistor in matlab

main.m
% Define parameters
Is = 1e-14;     % saturation current
Vt = 26e-3;     % thermal voltage
BF = 100;       % forward beta
BR = 1;         % reverse beta
VA = 100;       % Early voltage

% Define equations for Ebers-Moll model
f1 = @(vbe, ic) Is*(exp(vbe/Vt)-1) - BF*ic;
f2 = @(vbc, ic) Is*(exp(vbc/Vt)-1) - BR*ic;
f3 = @(vce, ic) ic - (Is*(exp(vbe/Vt)-1) - Is*(exp(vbc/Vt)-1))/(1+BF*exp(vbe/Vt)+BR*exp(vbc/Vt));

% Simulate transistor behavior for a given input signal
Vin = linspace(0, 1, 100);   % input voltage signal
Vcc = 5;                    % supply voltage
Rc = 1e3;                   % collector resistor

for ii = 1:length(Vin)
    vbe = Vin(ii);
    vbc = Vcc - vbe;
    
    % Solve for collector current
    ic = fsolve(@(x) [f1(vbe, x); f2(vbc, x); f3(vcc - Rc*x, x)], 1e-3);
    
    % Plot output characteristics
    plot(vce, vcc - Rc*ic, 'b')
    hold on
end
xlabel('Collector-emitter voltage (V)')
ylabel('Collector current (A)')
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