I use matlab to draw the curve between the ID and VDS of the transistor, but there is a jumping point in the middle. How can I smooth the curve?

Vgs=1.5;
W=3*10^-6;
L=0.5*10^-6;
Vth0=0.7;
landa=0.1;
u0=350*10^8;
tox=9*10^-9;
garma=0.45;
finf=0.9;
ebso=3.9*8.854*10^-12;
Cox=ebso/tox*10^-12;
kn=u0*Cox;
Vds=(0:0.001:3);
i=1;
for Vds1=(0:0.001:3)
    if Vds1<(Vgs-Vth0)
        Ids(i)=kn*W/L*[(Vgs-Vth0)*Vds1-0.5*Vds1^2];
        i=i+1;
    else
        Ids(i)=0.5*kn*W/L*(Vgs-Vth0)^2*(1+landa*Vds1);
        i=i+1;
    end
end
%Idsp=polyval(polyfit(Vds,Ids,10),Vds);
plot(Vds,Ids)

[CHENG WEI LI]

I do`not want to use polyfit

Answer 1

[Mathieu NOE]

hello

this would be my suggestion; replacing a segment between Vds = 0.5 and 1.5 with its smoothed version

Vgs=1.5;
W=3*10^-6;
L=0.5*10^-6;
Vth0=0.7;
landa=0.1;
u0=350*10^8;
tox=9*10^-9;
garma=0.45;
finf=0.9;
ebso=3.9*8.854*10^-12;
Cox=ebso/tox*10^-12;
kn=u0*Cox;
Vds=(0:0.001:3);
i=1;
for Vds1=(0:0.001:3)
    if Vds1<(Vgs-Vth0)
        Ids(i)=kn*W/L*[(Vgs-Vth0)*Vds1-0.5*Vds1^2];
    else
        Ids(i)=0.5*kn*W/L*(Vgs-Vth0)^2*(1+landa*Vds1);       
    end
    i=i+1;
end
%Idsp=polyval(polyfit(Vds,Ids,10),Vds);
ind = find(Vds>0.5 & Vds<1.5);

%% smoothing
Ids_smooth = Ids;

%%%%%%%%%%%%%%%%butterworth LP filtering)
NN = 3;
Wn = 0.003;
[B,A] = butter(NN,Wn);

figure(1)
% Ids_smooth(ind) = filtfilt(B,A,Ids(ind));
tmp = filtfilt(B,A,Ids);
Ids_smooth(ind) = tmp(ind);
plot(Vds,Ids,Vds,Ids_smooth)
legend('original','smoothed');

[Mathieu NOE]

Hi

problem solved ?

[Mathieu NOE]

hello again

problem solved ?