Resonant Inc.
TRANSVERSELY-EXCITED FILM BULK ACOUSTIC RESONATOR WITH INTERDIGITAL TRANSDUCER WITH VARIED MARK AND PITCH

Abstract:

An acoustic resonator includes a piezoelectric plate with a back surface attached to a substrate. An interdigital transducer (IDT) including interleaved fingers is formed on the front surface of the piezoelectric plate, the IDT comprising multiple copies of a unit cell juxtaposed along a length of the IDT. Each unit cell includes a first pitch/mark zone having a first pitch P1 between adjacent fingers and a first mark M1 and a second pitch/mark zone having a second pitch P2 and a second mark M2, where P.sub.2 is not equal to P.sub.1 and M.sub.2 is not equal to M.sub.1. A radio frequency signal applied to the IDT causes the first pitch mark zone and the second pitch/mark zone to excite a same shear primary acoustic mode in the piezoelectric plate.