Balanced filter structure utilizing bulk acoustic wave resonators having different areas
US6278342A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 28, 1999 |
| Grant date | Aug 21, 2001 |
| Priority date | — |
| Expiry date | Dec 28, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H9/568
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
The invention relates to resonator structures of radio communication apparatus, especially bulk acoustic wave filter structures. According to the invention, a bulk acoustic filter structure is constructed with a lattice configuration, in which two of the filters have a different area than other two for creating very steep passband edges in the frequency response of the filter. Preferably, the filter structure further comprises a second lattice structure for increasing the stopband rejection ratio of the filter structure, and for allowing the use of a simple mechanical structure. The cascaded configuration allows the construction of the filter structure in such a way, that the electrodes of the input and output port are at the same layer, thereby removing the need to make vias in the piezoelectric layer, which results in considerable simplification of the manufacturing process. Preferably, an acoustical mirror structure is used as the acoustical isolation in order to further simplify the mechanical structure of the filter structure.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.