Thin film bulk acoustic wave filters for GPS

The design and analysis of ladder filters are discussed, and reports on progress to date in the implementation of these devices for Global Positioning System (GPS) applications are summarized. Results are described for a two-dimensional plate wave analysis that illustrates the effects of resonator size on spurious resonances that degrade filter performance. Ladder filters in the series/shunt configuration are fabricated with 5-12 resonators on a common membrane of AlN supported by a silicon substrate. Preliminary experimental results show that the ladder filters have a clean out-of-band response with some spurious responses near the passband region. The filter insertion loss in the experimental devices requires improvement.<
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