Circuit analysis

[Guest snash]

Hi there.

I don't know too much about electronics analysis but i need to figure out the transfer function, i mean.. the Vo/Vi from the attached circuit.
Could someone help me?

Thanks

[audioguru]

R2 and the signal's source impedance form a voltage divider. C2 and the signal's source impedance form a lowpass filter.

R3 and R4 form another voltage divider that loads down the first voltage divider.

C3 and R3 form a highpass filter.

R3 and C4 form another lowpass filter.

The signal's source impedance in series with R3 calculated with R1 set the DC and very low frequency voltage gain of the opamp.

C1 and R1 form another lowpass filter.

[Guest BertEnders]

Some assumptions are required or there would be insufficient information to derive the transfer function.
From the given circuit, I assume that the source is an ideal voltage source and the amplifier block is an ideal op amp.

If those assumptions hold, the impedance block formed by R2||C2 will affect the current drawn from the source but will have no effect on the overall transfer function Vo/Vi (call it Av).  The impedance block formed by R4||C4 will have no effect at all, as the voltage at the inverting input is zero.

Av will be determined solely by the feedback impedance formed by R1||C1 and the input impedance formed by R3||C3.

At DC, Av is R1/R3.  For AC input, the reactance values of C1 and C3 make my head hurt too much to think about it right now.  It's taken me eight months to get this far.


Of course, I could be mistaken.  I'm sure it has happened before.  I think.

Hope this is of help to somebody,
Bert Enders