The below program is the Ids Vds characteristics of a DG MOSFET. and I am getting the error as Matrix dimensions must agree.. Please help me by fixing it

if true
  clear all;
hfin=1;
tsi=20
W=2*hfin*tsi;
Vth=1;
Leff=180;
DIBL=1.127*(W\Leff);
vth=Vth-DIBL;
lambda=25*10^-5;
u=1360;
ld=0.1;
Ec=1.5*106;
Cox=60;
Vds=0:0.5:10;
vgs=input('ENTER THE Vgs in volts');
m=length(Vds);
for i=1:m
if vgs < Vth
current(1,i)=0;
elseif Vds(i) >= (vgs - Vth)
current(1,i)=0.5* (vgs - Vth)^2*(1+lambda*Vds(i));
elseif Vds(i) < (vgs - Vth)
current(1,i)=((vgs-vth)*Vds(i))- 0.5*(Vds(i)^2)*(2*W*u*Cox/(Leff-ld+(Vds/Ec))+lambda*2*W*Cox/(Leff-ld)^2);
end
end
plot(Vds,current(1,:),'b')
xlabel('Vds, V')
ylabel('Drain Current,A')
title('I-V Characteristics of a MOSFET')

end

[ES]

I think there is a small misunderstanding of the concepts.. MOSFET works in linear region for certain voltage ranges and then saturates in some other region.. So you need two equations to draw its characteristics.. That is

if Mosfet in Linear region:
use Linear region's equation.
else
use Saturation region's equation.
end

In your code you have given the equation for only the linear region..

In the previous links I had sent you in the number of threads you have opened, there were IF and ELSE logics to handle it. Please go through them. You should also add the logic in a similar way. The equations there, are different because they are different MOSFETs, but all MOSFETs basically operate the same way, as to having different regions of operations..

http://www.stallinga.org/ElectricalCharacterization/tft/index.html

[ARTI]

 Sir, now I have added but still the same error
 if true
    clear all;
hfin=1;
tsi=20
W=2*hfin*tsi;
Vth=1;
Leff=180;
DIBL=1.127*(W\Leff);
vth=Vth-DIBL;
lambda=25*10^-5;
u=1360;
ld=0.1;
Ec=1.5*106;
Cox=60;
Vds=0:0.5:5;
A=3;
vgs=input('ENTER THE Vgs in volts');
Vdssat=(vgs-vth)/(1+(vgs-vth)/(Leff*Ec))
F=1-log(1+exp(A*(1-Vds/Vdssat))/log(1+exp(A)))
m=length(Vds);
for i=1:m
if vgs < Vth
current(1,i)=0;
current1(1,i)=0;
elseif Vds(i) >= (vgs - Vth)
current(1,i)=((vgs-vth)*Vds(i)-0.5*(Vds(i)^2))*(2*W*u*Cox/(Leff-ld+(Vds/Ec))+lambda*2*W*Cox/(Leff-ld)^2);
elseif Vds(i) < (vgs - Vth)
current(1,i)=((vgs-vth)*F*Vdssat(i)-0.5*F*(Vdssat(i)^2))*(2*W*u*Cox/(Leff-ld+(F*Vdssat/Ec))+lambda*2*W*Cox/(Leff-ld)^2);
end
end
plot(Vds,current(1,:),'b')
xlabel('Vds, V')
ylabel('Drain Current,A')
title('I-V Characteristics of a MOSFET')

end

Answer 1

[ES]

See the attached file and modified code..

clear all;
hfin=1;
tsi=20
W=2*hfin*tsi;
Vth=1;
Leff=180;
DIBL=1.127*(W\Leff);
vth=Vth-DIBL;
lambda=25*10^-5;
u=1360;
ld=0.1;
Ec=1.5*106;
Cox=60;
Vds=0:0.5:10;
vgs=input('ENTER THE Vgs in volts');
m=length(Vds);
for i=1:m

if vgs < Vth
current(1,i)=0;
current1(1,i)=0;
elseif Vds(i) >= (vgs - Vth)
current(1,i)=0.5* DIBL * ((vgs - Vth)^2)*(1+lambda*Vds(i));%Added DIBL
elseif Vds(i) < (vgs - Vth)
current(1,i)= DIBL*((vgs-Vth)*Vds(i) - 0.5*(Vds(i)^2))*(1+lambda*Vds(i)); %Simplified equation by approximation
end

end
plot(Vds,current(1,:),'b')
xlabel('Vds, V')
ylabel('Drain Current,A')
title('I-V Characteristics of a MOSFET')

[ARTI]

Thank you very much sir.

[ARTI]

Sir can you please tell me how you have modified as I have to explain to my faculty.

[ES]

%kn=un*cox = 100 microA/Volts cox is the capacitance of the oxide layer W and L or dimensions of the gate (width and length) i think.. kn=1e-4; DIBL=kn*W/L;

[User _X]

A pretty useful and accurate code for the DG MOS!!

[User _X]

I am trying to create the matlab code for the Ids - Vgs characteristics of a TG MOSFET, but I face several difficulties. Could I aks for help with this one?

Answer 2

[ES]

Fine that you have handled the linear and saturation region now..:) There were two small issues.. I have changed them below..

clear all;
hfin=1;
tsi=20
W=2*hfin*tsi;
Vth=1;
Leff=180;
DIBL=1.127*(W\Leff);
vth=Vth-DIBL;
lambda=25*10^-5;
u=1360;
ld=0.1;
Ec=1.5*106;
Cox=60;
Vds=0:0.5:10;
vgs=input('ENTER THE Vgs in volts');
m=length(Vds);
for i=1:m
if vgs < Vth
current(1,i)=0;
elseif Vds(i) >= (vgs - Vth)
current(1,i)=0.5* DIBL*(vgs - Vth)^2*(1+lambda*Vds(i));%Added DIBL
elseif Vds(i) < (vgs - Vth)
current(1,i)=((vgs-vth)*Vds(i))- 0.5*(Vds(i)^2)*(2*W*u*Cox/(Leff-ld+(Vds(i)/Ec))+lambda*2*W*Cox/(Leff-ld)^2);%Addedvds(i) instead of vds
end
end
plot(Vds,current(1,:),'b')
xlabel('Vds, V')
ylabel('Drain Current,A')
title('I-V Characteristics of a MOSFET')

[garima jain]

sir can you please help with tfets,poisson equations