Surface acoustic wave filters

摘要

Filter structures are described consisting of a plurality of individual surface acoustic wave (SAW) resonators formed of inter-digitated metallic combs on a common piezoelectric substrate. Areas of metallisation (1, 2, 3, 4) between the combs provide means to connect the filter in a circuit, e.g. in a mobile telephone unit to act as a filter with a passband in the 800 to 2200 MHz range. The individual SAW resonators differ from one another and are interconnected in ladder and/or balanced bridge arrangements.