I have a circuit that I want to gain its transfer function.I've attached a JPG file.

Plz look at my JPG file. How can I find its transfer function???

Thank you so much.

[Azzi Abdelmalek]

Do you need Matlab to do it ?

[vahid torabi]

Yes I want to do that by using matlab

Answer 1

[Shoaibur Rahman]

Input voltage (across left C) = Vi

Output voltage (across right C) = Vo

Apply voltage divider rule in RL and C (at right) branch:

Vo = ((1/jwC)/(R+jwL+1/jwC))*Vi, that gives the transfer function H:

H(jw) = Vo/Vi = (1/jwC)/(R+jWL+1/jwC) = |Ho(jw)|e^(j*theta0)

where, Ho(jw) = abs(H(jw)) and theta0 = angle(H(jw))

Matlab code:

R = 1; L = 1; C = 1; % use values what you want
w = 0:0.1:10*pi; % define the frequency range
H = 1./(1+w.^2*L*C+1j*w*R*C);
H0 = abs(H);
theta0 = angle(H);
subplot(211), plot(w,H0)
subplot(212), plot(w,theta0)

[vahid torabi]

Thank you so much for answering me dear Rahman.

[vahid torabi]

Thank you so much sir; but : H = 1./(1-w.^2*L*C+1j*w*R*C) is correct. Am I right??? you wrote 1./(1+w.^2*L*C+1j*w*R*C)!

[Shoaibur Rahman]

Yes, you are correct! j^2 = -1.