I'm looking into the input of and RC bandpass filter. I don't remember how to calculate the impedance looking into the circuit.

I was thinking I could transform the filter into the s-domain (laplace) to make the calculation easier, but this is only a guess.

I'm asking this question because I want to take my present bandpass filter and make it a "balanced" filter. Before adding the additional RC to accomplish this, I want to determine the impedance. After adding the additional RC the impedance should be the same.

Thanks,