Patent ID: 11894835
Assignee: MURATA MANUFACTURING CO., LTD.
Field: Basic communication processes (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A filter device comprising:
a substrate having at least a first cavity and a second cavity on a single die comprised of a plurality of layers;
a first piezoelectric plate spanning the first cavity and the second cavity;
a first interdigital transducer (IDT) on a front surface of the first piezoelectric plate that is opposite the substrate, the first IDT having interleaved fingers over the first cavity;
a second IDT on the front surface of the first piezoelectric plate and having interleaved fingers over the second cavity;
a first dielectric layer on the first piezoelectric plate, covering the first IDT and covering the second IDT;
a second piezoelectric plate on a surface of the first dielectric layer, over the first cavity and over the second cavity, such that the first and second IDTs are sandwiched between the first and second piezoelectric plates; and
a second dielectric layer on a front surface of the second piezoelectric plate opposite the first dielectric layer and over the first cavity but not over the second cavity,
wherein the second dielectric layer is coupled to the front surface of the second piezoelectric plate without any electrodes therebetween.