Optimal acoustic impedance materials for polished substrate coating to suppress passband ripple in BAW resonators and filters
US8952768B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 20, 2013 |
| Grant date | Feb 10, 2015 |
| Priority date | — |
| Expiry date | Aug 27, 2033 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H9/175
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A bulk acoustic wave (BAW) resonator is constructed to reduce phase and amplitude ripples in a frequency response. The BAW resonator is fabricated on a substrate 400 μm thick or less, preferably approximately 325 μm, having a first side and a polished second side with a peak-to-peak roughness of approximately 1000 A. A Bragg mirror having alternate layers of a high acoustic impedance material, such as tungsten, and a low acoustic impedance material is fabricated on the first side of the substrate. A BAW resonator is fabricated on the Bragg mirror. A lossy material, such as epoxy, coats the second side of the substrate opposite the first side. The lossy material has an acoustic impedance in the range of 0.01× to 1.0× the acoustic impedance of the layers of high acoustic impedance material.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.