###  Calculate the current gain and plot fT versus collector current


ac_base_data = getresult('CHARGE','ac_base');
f = ac_base_data.f;
Nf = length(f);
Ib = pinch(ac_base_data.dI);
Ib = pinch(Ib(1:8,2,1:Nf));
ac_collector_data = getresult('CHARGE','ac_collector');
Ic = pinch(ac_collector_data.dI);
Ic = pinch(Ic(1:8,2,1:Nf));

I_gain = Ic/Ib;  # small signal current gain

plot(f,log10(abs(I_gain(8,1:Nf))),'freq (Hz)','small-signal current gain','','log10x');
fT=matrix(8,1);
for (i = 1:8) {
kern = find(abs(I_gain(i,1:Nf))<=1);
fT(i) = f(kern(1));
}

dc_data = getresult('CHARGE','collector');
Ic_dc = pinch(dc_data.I);  # DC collector current

plot(Ic_dc(2:8)*1e-4*1e9,fT(2:8),'Ic (nA/um)','fT (Hz)','','log10x,log10y');