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I'm trying to find the transfer function to this circuit (see attached image). I put together a matlab script file which I will paste the code below. I found the transfer function to be:

((s*L4+1)/s/C3/(s*L4+1+1/s/C3)+L2/C2/(s*L2+1/C2/s))/s/C1/((s*L4+1)/s/C3/(s*L4+1+1/s/C3)+L2/C2/(s*L2+1/C2/s)+1/s/C1)/(((s*L4+1)/s/C3/(s*L4+1+1/s/C3)+L2/C2/(s*L2+1/C2/s))/s/C1/((s*L4+1)/s/C3/(s*L4+1+1/s/C3)+L2/C2/(s*L2+1/C2/s)+1/s/C1)+1)

Can someone verify this is correct?

Matlab Code:

% Convert to S-domain

R1 = 1

C1 = sym('1/(s*C1)')

C2 = sym('1/(s*C2)')

L2 = sym('s*L2')

C3 = sym('1/(s*C3)')

L4 = sym('s*L4')

RL = 1

% L4 in series with RL

Zeq1 = L4 + RL

% Zeq1 in parallel with C3

Zeq2 = (Zeq1*C3)/(Zeq1 + C3)

simple(Zeq2)

% L2 and C2 in parallel

Zeq3 = (L2*C2)/(L2 + C2)

simple(Zeq3)

% Zeq2 in series with Zeq3

Zeq4 = Zeq2 + Zeq3

simple(Zeq4)

% Zeq4 in parallel with C1

ZL = (Zeq4*C1)/(Zeq4 + C1)

simple(ZL)

% Voltage division to get Transfer Function

T = ZL/(ZL+R1)

simple(T)

pause

Thanks!

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# Homework Help: 4th Order Elliptic Filter

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