Piezoelectric resonator and piezoelectric filter
US5400001A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 20, 1993 |
| Grant date | Mar 21, 1995 |
| Priority date | — |
| Expiry date | Sep 20, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H9/605
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
In a piezoelectric resonator having a piezoelectric bar formed in a substantial rectangular parallelopiped and electrodes formed on a pair of confronting surfaces of the piezoelectric bar for resonating in the length expander mode, the piezoelectric bar has at least a bevel portion extending the longitudinal direction. In a ladder filter having series and parallel piezoelectric resonators, the series piezoelectric resonator has the bevel portion to shift a frequency of a spurious response to that of the parallel piezoelectric resonator to suppress the spurious response. It is disclosed that a second piezoelectric resonator has a piezoelectric bar formed in a rectangular parallelopiped has a length L, a width W, and a thickness T wherein L>W>T; and electrodes formed on a pair of confronting surfaces defined by L and T. Another ladder filter includes the second piezoelectric resonator as the series resonator to decrease a capacitance between the electrodes to increase an amount of attenuation. In the second piezoelectric resonator, when W<T and 0.42<T/L<2.5, a coupling factor is large.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.