If A_FT is the total passband gain, f_L is low cutoff frequency, f_H is high cutoff frequency, then voltage gain magnitude of a band‐pass filter is given by:

Bandpass filter

A band-pass filter (BPF) is a device that passes frequencies within a certain range and rejects (attenuates) frequencies outside that range.

It is formed by cascading a low and high pass filter.

The cut-off frequency of the low pass filter is f_H and the cut-off frequency of the high pass filter is f_L. When these two filters are cascaded, the total pass band of the bandpass filter lies between f_H and f_L.

The voltage gain magnitude of a band‐pass filter is given by:

\(\begin{vmatrix}\rm \frac{v_0}{v_{in}}\end{vmatrix}= \rm \frac{A_{AF}(f/f_L)} {\sqrt{[1+(f/f_L)^2][1+(f/f_H)^2]}}\)

where, A_AF = Total passband gain

fH = High cutoff frequency (Hz)

f_L = Low cutoff frequency (Hz) 

f = Operating frequency