ABSTRACT
Surface acoustic wave (SAW) components have been commercially available for over 20 years. Common SAW device types include bandpass filters, delay lines, dispersive devices, resonators, and resonator filters. The basic principles of operation of most SAW device types are best introduced by considering the concrete example of a transversal SAW filter. A transversal SAW filter consists of two transducers with interdigital arrays of thin metal electrodes deposited on a highly polished piezoelectric substrate. SAW devices are currently utilized for numerous commercial, consumer, and military applications. The type of device commonly used for each application can be categorized based on the generic components that make up the SAW device. These components include bidirectional and unidirectional transducers, dispersive or “chirp” transducers, and reflectors. Bidirectional transversal filters constitute the most widely used application of SAW technology. Low-loss SAW filters are required for certain applications where system noise figure or dynamic range cannot accommodate the higher loss typical of bidirectional SAW filters.
