CPC H03H 9/568 (2013.01) [H03H 3/02 (2013.01); H03H 3/04 (2013.01); H03H 9/02015 (2013.01); H03H 9/02157 (2013.01); H03H 9/02228 (2013.01); H03H 9/174 (2013.01); H03H 9/205 (2013.01); H03H 9/54 (2013.01); H03H 9/564 (2013.01); H03H 9/566 (2013.01)] | 20 Claims |
1. A filter device, comprising:
a substrate;
at least one piezoelectric layer attached directly to the substrate or by one or more intermediate material layers, the at least one piezoelectric layer comprising a plurality of diaphragms that are over a plurality of cavities, respectively, in at least one of the substrate and the one or more intermediate material layers, wherein:
a first portion of the at least one piezoelectric layer has a first thickness, and
a surface of a second portion of the at least one piezoelectric layer is recessed relative to a surface of the first portion of the at least one piezoelectric layer such that the second portion of the at least one piezoelectric layer has a second thickness less than the first thickness; and
a conductor pattern at the first and second portions of the at least one piezoelectric layer, the conductor pattern comprising:
a first interdigital transducer (IDT) with interleaved fingers on a diaphragm having the first thickness, and
a second IDT with interleaved fingers on a diaphragm having the second thickness.
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