Crystal filter

A crystal filter is an electronic filter that uses quartz crystals for resonators. Quartz crystals are piezoelectric, so their mechanical characteristics can affect electronic circuits. (see mechanical filter) In particular, quartz crystals can exhibit mechanical resonances with a very high Q factor (from 10,000 to 100,000 and greater — far higher than conventional resonators built from inductors and capacitors). The crystal's stability and its high Q factor allow crystal filters to have precise center frequencies and steep band-pass characteristics. Typical crystal filter attenuation in the band-pass is approximately 2-3dB. Crystal filters are commonly used in communication devices such as radio receivers.