In electronics, a bandpass filter is a circuit with a frequency response that has one bandpass in the centre, surrounded by two stopbands.
Why use a bandpass filter? It’s so that we can “tune” our circuit into a specific, small range of frequencies (think a tuner or a radio).
Bandpass transfer functions are second-order, because we essentially have a high-pass circuit on the lower end and a low-pass circuit on the higher end of the frequency interval.
Circuits
We can build a bandpass filter using an op amp in feedback configuration. This allows us to prevent loading one of the other sub-circuits.
We can also use the series RLC circuit where:
