Resonant Inc.
TRANSVERSELY-EXCITED FILM BULK ACOUSTIC RESONATOR USING PRE-FORMED CAVITIES

Abstract:

Acoustic resonator devices and filters are disclosed. An acoustic resonator device includes a substrate having a surface, wherein the surface comprises an etched cavity, and a single-crystal piezoelectric plate having parallel front and back surfaces, the back surface attached to the surface of the substrate except for a portion of the piezoelectric plate forming a diaphragm that spans the cavity. An interdigital transducer (IDT) is formed on the front surface of the single-crystal piezoelectric plate, wherein interleaved fingers of the IDT are aligned with the cavity such that the interleaved fingers are disposed on the diaphragm. The IDT is configured to excite a primary acoustic mode in the diaphragm in response to a radio frequency signal applied to the IDT.