Longitudinally coupled double mode resonator filters using shallow bulk acoustic waves
US6472959B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 7, 2000 |
| Grant date | Oct 29, 2002 |
| Priority date | — |
| Expiry date | Mar 7, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H7/1708
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A filter comprises a shallow bulk acoustic wave (SBAW) longitudinally coupled double mode resonator (LCR) and a reactance coupled between an input and an output of the resonator. Due to its use of a piezoelectric substrate with high electromechanical coupling and an orientation for propagating SBAWs, the resonator has a relatively poor stop band attenuation in a shoulder region on a high frequency side of its pass band. At frequencies in the shoulder region, a signal coupled via the resonator from the input to the output is reduced by a signal of opposite phase coupled via the reactance with a similar attenuation, thereby improving attenuation in the shoulder region. The reactance can be a capacitance formed on the substrate surface.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.