Wide-bandwidth monolithic crystal filter
US4229718A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 19, 1979 |
| Grant date | Oct 21, 1980 |
| Priority date | — |
| Expiry date | Apr 19, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H9/56
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A monolithic crystal filter is disclosed that provides much wider bandwidths than were obtainable by prior art crystal filters. The inventive wide-bandwidth monolithic filter includes a piezoelectric substrate, an output electrode, a plurality of input electrodes arranged in orthogonal relationship with the output electrode and common electrodes disposed opposite to the input and output electrodes. The input and output electrodes are preferably disposed on the substrate along the crystallographic axes thereof. Increased bandwidth is realized due to the increased coupling resulting from the combination of the individual couplings from each input electrode at the outputelectrode. As a result of the increased coupling provided by the inventive crystal filter, overtone mode operation is now possible at much higher frequencies which heretofore were not obtainable by prior art crystal filters due to impractically close electrode spacing requirements.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.