Patent ID: 11967942
Assignee: MURATA MANUFACTURING CO., LTD.
Field: Basic communication processes (Electrical engineering)
Classification: CPC H | IPC H

Claim 18:
19. A radio frequency filter device comprising:
a substrate having a base layer and an intermediate dielectric layer with a plurality of cavities extending therein;
at least one single-crystal piezoelectric plate attached to a surface of the intermediate layer of the substrate except for portions of the at least one piezoelectric plate forming a plurality of diaphragms, each of which spans a respective cavity in the substrate; and
a conductor pattern on the at least one single-crystal piezoelectric plate and defining a ladder filter circuit including a plurality of acoustic resonators, one or more resonators from the plurality of acoustic resonators divided respectively into one or more pairs of sub-resonators,
wherein each sub-resonator comprises an interdigital transducer (IDT) with interleaved fingers disposed on a diaphragm of the plurality of diaphragms, respectively, and
wherein each pair of sub-resonators is arranged in symmetrical positions with respect to a central axis of the filter device,
wherein the plurality of acoustic resonators includes two or more series resonators and two or more shunt resonators, and
wherein the two or more series resonators are disposed in sequence along the central axis of the device and the two or more shunt resonators are disposed outboard of the series resonators.