Surface Wave Resonator and Bulk Wave Crystal Filters.

摘要

This report details a 32 month research project on surface acoustic wave, SAW, two port resonator filters, phase weighted gratings for surface wave resonators, and the equivalent circuit modeling of a thin film stacked crystal bulk wave filter. The report details a new device configuration for coupled two port SAW resonators which would allow the coupling to occur only when the grating reflectors are in resonance and would offer little coupling when the resonator is out of the resonance condition. This configuration is composed of an interdigital electrode transducer, IDT, which is placed within the grating itself but is an IDT whose periodicity is an even multiple of the wavelength. The concept of a phase weighted grating is described for use in wide band resonators. This new concept is based upon the unique properties of gratings and the concept of a movable reflection plane. A simple equivalent circuit for the thin film stacked crystal filter is derived for the first time and results in a lumped element representation for this important device. (Author)