Acoustic reflector for a BAW resonator providing specified reflection of both shear waves and longitudinal waves
US6933807B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 7, 2003 |
| Grant date | Aug 23, 2005 |
| Priority date | — |
| Expiry date | Dec 13, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H9/175
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A BAW resonator includes a piezoelectric layer, a first electrode, a second electrode, a substrate, and an acoustic reflector disposed between the substrate and the second electrode. The acoustic reflector has a plurality of layers. A performance of the acoustic reflector is determined by its reflectivity for a longitudinal wave existing in the BAW resonator at the resonance frequency of the BAW resonator and by its reflectivity for a shear wave existing in the BAW resonator at the resonance frequency of the BAW resonator. The layers of the acoustic reflector and layers disposed between the acoustic reflector and the piezoelectric layer are selected, with reference to their number, material, and thickness, such that the transmissivity for the longitudinal wave and the transmissivity for the shear wave in the area of the resonance frequency is smaller than −10 dB.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.