How can I find where those indesirabe plots are from ?

Hello.

I am running the following code:

%% Ids(Vds) %% 

mu=10;
Cox=3.9;
W=360*(10^(-9));
L=180*(10^(-6));
K=(mu*Cox)*(W/L);
Vth=1;
vds=0:0.2:20;
vgs=0:0.2:20;

 n=length(vgs);
 m=length(vds);
 for j=1:n
 for i=1:m
     if vgs(j) < Vth
     current(1,i)=0;
         elseif vds(i) >= (vgs(j) - Vth)
         current(1,i)=0.5* K * (vgs(j) - Vth)^2;
         elseif vds(i) < (vgs(j) - Vth)
         current(1,i)= K*((vgs(j)-Vth)*vds(i) - 0.5*(vds(i)^2));
         hold on
     end
 plot(vds,current(1,:),'b')
 xlabel('Vds (V)')
 ylabel('Drain Current (A)')
 title('I-V Characteristics of a MOSFET')
 end
 end
 hold off;

And this is what I obtain when I plot the thing you can see in the attached file.

As you can see, there are some vertical plots that made a very beatiful spider-net-shape but this not what I am looking for.

I tried to change, kinda randomly I assume, some things in the loop but it didn't work.

Thank you for your help !

[Abderrahim. B]

So how should look like the plot you want? removing those 'vertical' lines ?

Answer 1

[Mathieu NOE]

hello

maybe this ?

%% Ids(Vds) %% 
mu=10;
Cox=3.9;
W=360*(10^(-9));
L=180*(10^(-6));
K=(mu*Cox)*(W/L);
Vth=1;
vds=0:0.2:20;
vgs=0:0.2:20;
 n=length(vgs);
 m=length(vds);
 
 for j=1:n
     for i=1:m
         if vgs(j) < Vth
         current(1,i)=0;
             elseif vds(i) >= (vgs(j) - Vth)
             current(1,i)=0.5* K * (vgs(j) - Vth)^2;
             elseif vds(i) < (vgs(j) - Vth)
             current(1,i)= K*((vgs(j)-Vth)*vds(i) - 0.5*(vds(i)^2));
             hold on
         end
     end
     plot(vds,current(1,:),'b')
     xlabel('Vds (V)')
     ylabel('Drain Current (A)')
     title('I-V Characteristics of a MOSFET')
 end
 hold off;

[Ilan Boulet]

Thanks a lot !

[Mathieu NOE]

My pleasure !