Surface-acoustic-wave resonator filters

This paper presents an overview of surface-acoustic-wave (SAW) resonator filter technology. Given the current state of the art, these filters promise reproducible low-loss (≲6 dB) narrow-bandwidth (500 ≲ f/Δf ≲ 50 000) responses in the VHF and UHF ranges. Devices that contain one or a number of sections, each consisting of a resonant cavity between two grating reflectors and an input and output coupling mechanism, are considered. The initial discussion describes the layout, theoretical characteristics, and typical experimental responses of singlesection two-port filters. The subsequent discussion focuses on multisection devices using any of various intercavity coupling techniques. A generalized analysis and design formalism based on wave-scattering theory is reviewed, and experimental results from a number of device prototypes are given. Finally, practical design and fabrication trade-offs and performance ranges are summarized for a number of configurations.