Question

Design second (2'd) order Butterworth BPF with lower cut-off frequency 3KHz and higher cut-off frequency = 7KHz. Draw the cct diagram, frequency response, give its slope (roll-off) and overall gain (Av)?

Answer 1

A second order Butterworth Bandpass Filter (BPF) can be designed by cascading two first order Butterworth filters. The circuit diagram consists of two cascaded first order Butterworth filters connected in series. The frequency response has a peak at the center frequency, which is the geometric mean of the lower and higher cutoff frequencies. The slope or roll-off of the filter is 40 dB/decade or 12 dB/octave. The overall gain (Av) of the filter is unity (1) in the passband.

Designing a Second Order Butterworth Bandpass Filter