Band-stop filter

A band-stop filter, band stop filter or also called in audio engineering tub filter is in electrical engineering, a filter, which attenuates a specific, usually wide frequency band and in the limiting case can not happen. This series and parallel resonant circuits are compared to the bandpass reversed in analog circuit structures, resulting in the opposite thereto behavior results.

In contrast to a notch filter (English notch filter ) which has the transfer function of a single zero which is ideally set to an accuracy of only be suppressed frequency, can the transfer function of the band-stop filter also comprise different zero points and thus comprise a wider range in the stop band.

As a band-stop cutoff frequencies of those frequencies are defined, wherein the ratio of output to input voltage,

-3 [ [ Decibels ] | dB] is.

The center frequency is the geometric mean of the upper and lower cut-off frequency:

The static frequency response change, the emphasis and the de-emphasis rather than the cut-off frequency, the time constant is usually expressed.

In audio engineering, special band-stop filters which dampen the mid-frequency range of an audio signal relative to the low and high sound frequencies, also referred to as bath filter. The term describes the course of the magnitude frequency response of these filters.