Multiple pole bandpass filter having monolithic crystal elements
US4423394A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 6, 1977 |
| Grant date | Dec 27, 1983 |
| Priority date | — |
| Expiry date | Jun 6, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H9/542
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A symmetrical two pole monolithic crystal filter is combined with appropriate value fixed capacitors and cascaded with other similar filter elements to provide a high order filter with symmetrical transmission zeros and low passband ripple. The filter includes a piezoelectric resonating element having first and second opposite sides with first and second pairs of electrodes thereon. A first capacitor is coupled to an electrode of the first pair located on the first side and a second capacitor is coupled to an electrode of the second pair of the electrodes located on the first side. A shunting capacitor is used between the electrodes of the first and second pairs located on the first side. A fourth capacitor is coupled from both of the first and second electrodes located on the second side.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.