A filter is a circuit that is capable of passing a specific range of frequencies while blocking other frequencies. As you discovered in Chap. 2, the four major types of filters include low-pass filters, high-pass filters, bandpass filters, and notch filters (or band-reject filters). A low-pass filter passes low-frequency components of an input signal, while a high-pass filter passes high-frequency components. A bandpass filter passes a narrow range of frequencies centered around the filter’s resonant frequency, while a notch filter passes all frequencies except those within a narrow band centered around the filter’s resonant frequency.
Filters have many practical applications in electronics. For example, within a ...