Bandpass filter with frequency separation between shunt and series resonators set by dielectric layer thickness
US10917070B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 20, 2019 |
| Grant date | Feb 9, 2021 |
| Priority date | — |
| Expiry date | Nov 20, 2039 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10N30/877
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
Filter devices and methods of fabrication are disclosed. A filter device includes a piezoelectric plate attached to a substrate, portions of the piezoelectric plate forming diaphragms spanning respective cavities in the substrate. A conductor pattern formed on a surface of the piezoelectric plate includes a plurality of interdigital transducers (IDTs) of a respective plurality of acoustic resonators including a shunt resonator and a series resonator, interleaved fingers of each of the plurality of IDTs disposed on one of the diaphragms. Radio frequency signals applied to the IDTs excite respective primary shear acoustic modes in the respective diaphragms. A thickness of a first dielectric layer disposed on the front surface between the fingers of the IDT of the shunt resonator is greater than a thickness of a second dielectric layer disposed on the front surface between the fingers of the IDT of the series resonator.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.