Filters using transversly-excited film bulk acoustic resonators with frequency-setting dielectric layers

Abstract

A filter device is provided that includes a substrate; a piezoelectric layer coupled to the substrate either directly or via one or more intermediate layers; a first interdigital transducer (IDT) of a first bulk acoustic resonator device on the piezoelectric layer and having interleaved fingers over a first cavity the first bulk acoustic resonator device; a second IDT of a second bulk acoustic resonator device on the piezoelectric layer and having interleaved fingers over a second cavity of the second bulk acoustic resonator device; a first dielectric layer having a first thickness disposed between the interleaved fingers of the first IDT; and a second dielectric layer having a second thickness disposed between the interleaved fingers of the second IDT. The first thickness is greater than the second thickness.

Dependencies are inferred from the claim text.