Warning: Imaginary parts of complex X and/or Y arguments ignored. > In Finalv3test (line 19) Warning: Imaginary parts of complex X and/or Y arguments ignored. > In Finalv3t

% NPN JFET Simulation
% Variation 1: Metallurgical channel thickness (a)
% Variation 2: Channel width-to-length (LW)
% Define parameters
IDSS = 10; % Saturation current (mA)
VGSoff = -4; % Gate-source cutoff voltage (V)
VP = -6; % Pinch-off voltage (V)
RD = 1000; % Drain resistance (ohm)
% Variation 1: Metallurgical channel thickness (a)
a = linspace(50, 150, 100); % Vary a from 50 Å to 150 Å
% Calculate drain current (ID) for each value of a
ID1 = IDSS * (1 - (abs(VGSoff) / VP).^sqrt(2)) .^2;
% Plot the results
figure;
plot(a, ID1, 'b', 'LineWidth', 2);

Warning: Imaginary parts of complex X and/or Y arguments ignored.

xlabel('Metallurgical Channel Thickness (Å)');
ylabel('Drain Current (mA)');
title('Change in Drain Current with Metallurgical Channel Thickness');

% Variation 2: Channel width-to-length (LW)
LW = linspace(4, 10, 100); % Vary LW from 4 to 10
% Calculate drain current (ID) for each value of LW
ID2 = IDSS * (1 - (abs(VGSoff) / VP).^sqrt(2)) .^ (2 * LW - 1);
% Plot the results
figure;
plot(LW, ID2, 'r', 'LineWidth', 2);

Warning: Imaginary parts of complex X and/or Y arguments ignored.

xlabel('Channel Width-to-Length (LW)');
ylabel('Drain Current (mA)');
title('Change in Drain Current with Channel Width-to-Length');

% Display the maximum drain current for each variation
disp(['Maximum Drain Current (Variation 1): ', num2str(max(ID1)), ' mA']);

Maximum Drain Current (Variation 1): 10.2752+12.4955i mA

disp(['Maximum Drain Current (Variation 2): ', num2str(max(ID2)), ' mA']);

Maximum Drain Current (Variation 2): -488.6218+832.583i mA

Answer 1

[Torsten]

(abs(VGSoff) / VP)

is negative, thus

(abs(VGSoff) / VP)^sqrt(2)

produces complex numbers.

Thus ID1 and ID2 are complex-valued.

Thus MATLAB cannot make the plots

plot(LW, ID1, 'r', 'LineWidth', 2);
plot(LW, ID2, 'r', 'LineWidth', 2);

Instead, it plots

plot(LW, real(ID1), 'r', 'LineWidth', 2);
plot(LW, real(ID2), 'r', 'LineWidth', 2);