ABSTRACT
Ceramic filters are filter components that make use of piezoelectric ceramics. The design principles for ceramic filters are almost the same as for crystal filters. Ceramic filters have many merits that are different from crystal filters. The differences are based on the piezoelectric materials used for these filters. The most common piezoelectric ceramic filter materials are lead zirconate/lead titanate. Ceramic filters are composed of many kinds of ceramic resonators. A piezoelectric ceramic resonator is a small, thin piece of piezoelectric ceramic with metallized electrodes on the opposite surfaces. Ceramic filters are widely used for AM radio receivers and communications equipment in the frequency range from 400 to 500 kHz. The ceramic filter is widely used for FM radio receivers, television sound intermediate frequency, and communications equipment in the frequency range between 3 and 30 MHz. Ceramic filters are widely used for consumer markets. Resonators are enclosed in a plastic case or resin coating instead of a hermetic seal.
