SAW filter


A Surface Acoustic Wave (SAW) filter is a filter whereby the electrical input signal is converted to a acoustic wave by so-called interdigital transducers (IDTs) on a piezoelectric substrate such as quartz. The IDTs consist of interleaved metal electrodes which are used to launch and receive the waves, so that an electrical signal is converted to an acoustic wave and then back to an electrical signal.


The most common group of SAW-filters are bandpass filters, which are in very widespread use in radio systems (including mobile phone handsets and base stations) and in domestic TV. There are many types with differing advantages, such as low shape factor, low insertion loss, small size, or high-frequency operation. The wide variety of types is possible because almost arbitrary shapes can be defined on the surface with very high precision.

SAW filters are limited to frequencies from about 50 MHz up to 3GHz.