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Invalid expression. Check for missing multiplication operator, missing or

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Filip Vucak
Filip Vucak on 19 Jul 2021
Answered: Walter Roberson on 20 Jul 2021
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clc
%Constants
q=l.6e-19;
k=8.625e-5;
e0=8.854e-14;
%Device, Material, and System Parameters
ni=l.5e10;
esi=ll.8;
T=300;
a=l.5e-4;
z=50e-4;
L=5e-4;
ND=2el5;
VG=[0 -.5 -1 -1.5 -2];
%Contact Potential
V0=.55+k*T*log(ND/ni);
%mobility calculation
NDref=1.3el7;
mu_n_min=92;
mu_n_0=1268;
alpha_n=0.91;
mun=mu_n_min+mu_n_0./(1+(ND/NDref).^alpha_n)
%Resistivity
sigma=q*ND*mun;
rho=l/sigma;
%Mutual Transconductance
G0=2*a*z/(rho*L)
%Pinch—off voltage
VP=V0-q*a^2*ND/(2*e0*esi)
% Calculate ID as a function of VD
VD=linspace(0,abs(VP)+5,100);
for j=1:1:length(VG)
for i=1:1:length(VD)
if VD(i)<(VG(j)-VP) %Linear regime
ID(j,i)=G0*(VD(i)-2/3*(V0-VP)*(((VD(i)+V0-VG(j))/(V0-VP)).^(3/2)-((V0-VG(j))/(V0-VP)).^(3/2)));
else
VD(i)=VG(j)-VP;
ID(j,i)=G0*(VD(i)-2/3*(V0-VP)*(1-((V0-VG(j))/(V0-VP)).^(3/2)));
end
end
end
VD=linspace(0,abs(VP)+5,100); %Voltage vector re—generation for plotting
plot(VD,ID*le6)
hold on
xlabel ('VD (Volts)')
ylabel ('ID (Microampere) ')
title('JFET I—V Characteristics')
grid
%Code ends

Answers (2)

Image Analyst
Image Analyst on 19 Jul 2021
It doesn't like your decimal point. What is it? If I copy and paste your number into the command window, it complains about the decimal point but if I type it in myself directly, it works fine. Maybe you used some sort of higher order unicode decimal point.

Walter Roberson
Walter Roberson on 20 Jul 2021
q=l.6e-19;
The decimal point is fine, but that is a lower-case L, not a one, before the decimal point.

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