Analysis using non linear diode model
Under-voltage scenario. Top diode open
Simplifying
assumption
When diodes are
reverse biased
Implicit function. Must be evaluated
numerically
Is=1e-14;% MATLAB SCRIPT TO ANALYZE
n=1;     % UNDER-VOLTAGE
Rs=40;
vs=[-2:.2:2]';
vin=[];
for k=1:length(vs)
   x0=[vs(k);vs(k);Rs;Is];
   kcl=inline('((x(2)-x(1))/x(3)+x(4)*(exp(-39*x(1))-1))^2');
   x=fminsearch(kcl,x0);
   vin=[vin;x(1)];
end
plot(vs,vin,'bo',vs,vin,'r'), title('UNDER-VOLTAGE WITH NONLINEAR DIODE') xlabel('Source Voltage(v_S)[V]'), ylabel('Input Voltage(v_{in})[V]'),grid