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# Error using plot Vectors must be the same length.

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iicecont on 23 Feb 2021
Answered: Jan on 25 Feb 2021
I'm trying to plot ID VDS characteristics for my designed mosfet but after i try to run the code it shows "Error using plot Vectors must be the same length.".
here is my code, thanks in advance
clc; clear all; close all;
%parameters and define variable
syms x y;
un = 17215.771;
Kox = 4.2;
ep0 = 8.854e-12;
x0 = 50e-9;
Cox = ((Kox*ep0)/x0);
VTH = 0.5;
VGS = 2; % [V]
eqna = 20.10364e-6 == 0.5 * un * Cox * (y) * ((VGS - VTH).^2)*(1 + (x * 3.75));
eqnb = 20.34537e-6 == 0.5 * un * Cox * (y) * ((VGS - VTH).^2)*(1 + (x * 4));
eqns = [eqna eqnb];
S = solve(eqns, [x y]);
x = S.x;
y = S.y;
figure(3);
Vgs = (1:0.5:5);
Vds = (0:0.25:5);
[sz1,sz2] = size(Vgs);
for t = (sz1:sz2)
VDSAT2 = Vgs - VTH;
VDSS = (0:0.25:VDSAT2(t));
VDSS2 = Vgs(t) - VTH + 0.25:0.25:5;
IDLinear = un.*Cox.*y.*(((VDSAT2(t)).*VDSS)-((VDSS.^2)/2));
IDSat = 0.5.*un.*Cox.*y.*((VDSAT2(t)).^2).*(1+x.*(VDSS2));
[u,v] = size(VDSS);
[uu,vv] = size(Vds);
for q = (1:v)
ID(t,q) = IDLinear(1,q);
end
for r = (v+1:vv)
IDD(t,r) = IDSat(1,r-v);
end
plot(VDSS,ID,[VDSS2 5],[IDD IDD]);
hold on
end
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### Answers (1)

Jan on 25 Feb 2021
Use the debugger to find the cause of the problem. Type in the command line:
dbstop if error
Run the code again. If it stops, check the sizes of the arguments provided to plot:
size(VDSS)
size(ID)
size([VDSS2 5])
size([IDD IDD])
Something is not matching. Which one?
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