clear;

load('nmos_ac.ldev');

switchtolayout;

setnamed('CHARGE','log start frequency',1e9);
setnamed('CHARGE','log stop frequency',6e9);
setnamed('CHARGE','num frequency points per dec',80);

select("CHARGE::boundary conditions::gate");
set('bc mode','steady state');
set('sweep type','range');
set('range start',0);
set('range stop',2.5);
set('range interval',0.25);
set('apply ac small signal','all');

select("CHARGE::boundary conditions::drain");
set('bc mode','steady state');
set('sweep type','single');
set('voltage',5);
set('apply ac small signal','last');

run;

dc_gate_data = getresult('CHARGE','gate');
Vg = dc_gate_data.V_gate;
NV = length(Vg);
ac_gate_data = getresult('CHARGE','ac_gate');
f = ac_gate_data.f;
Nf = length(f);
Ig = pinch(ac_gate_data.dI);
Ig = pinch(Ig(1:NV,2,1:Nf));
f = ac_gate_data.f;
ac_drain_data = getresult('CHARGE','ac_drain');
Id = pinch(ac_drain_data.dI);
Id = pinch(Id(1:NV,2,1:Nf));

I_gain = Id/Ig;

fT = matrix(NV,1);

for (i = 1:NV) {
kern = find(abs(I_gain(i,1:Nf))<=1);
fT(i) = f(kern(1));
}

plot(Vg,fT*1e-9,'Vg (V)','fT (GHz)');

matlabsave('nmos_fT',Vg,fT);