Resonant Inc.
TRANSVERSELY EXCITED FILM BULK ACOUSTIC RESONATOR USING ROTATED Z-CUT LITHIUM NIOBATE

Abstract:

Acoustic resonator devices, filters, and methods are disclosed. An acoustic resonator includes a substrate and a lithium niobate (LN) plate having parallel front and back surfaces, the back surface attached to a surface of the substrate except for a portion of the LN plate forming a diaphragm that spans a cavity in the substrate. An interdigital transducer (IDT) is formed on the front surface of the LN plate such that interleaved fingers of the IDT 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. A direction of acoustic energy flow of the primary acoustic mode is substantially orthogonal to the surfaces of the diaphragm. The Euler angles of the LN plate are 0.degree., .beta., 90.degree., where .beta. is greater than or equal to -15.degree. and less than 0.degree..