Notch filters, also known as notch filters, are used to suppress unwanted frequencies. They are narrow-band, tunable notch filters that have only a small frequency range and whose passband curves can be changed.
Notch filters are used in LF technology and RF technology, in acoustics and in high- power cyclotrons. In audio technology, notch filters are used to suppress mains hum or rumble noise. They are built into equalizers and are tuned to the noise frequency. Notch filters should have a quality factor (Q) of at least 1 and at most 5 for an amplitude drop of 3 dB.
In general, the use of steep-edged notch filters involves certain risks, which are reflected in the changed phase positions and group propagation times.