| US 7,479,847 B2 | ||
| Filter using piezoelectric resonator | ||
| Takehiko Yamakawa, Osaka (Japan); Hiroshi Yamaguchi, Osaka (Japan); Hiroshi Nakatsuka, Osaka (Japan); Hiroyuki Nakamura, Osaka (Japan); Keiji Onishi, Osaka (Japan); and Toshio Ishizaki, Hyogo (Japan) | ||
| Assigned to Panasonic Corporation, Osaka (Japan) | ||
| Filed on Oct. 18, 2006, as Appl. No. 11/582,425. | ||
| Application 11/582425 is a continuation in part of application No. 10/984839, filed on Nov. 10, 2004, granted, now 7,138,888. | ||
| Claims priority of application No. 2003-391110 (JP), filed on Nov. 20, 2003; and application No. 2006-228111 (JP), filed on Aug. 24, 2006. | ||
| Prior Publication US 2007/0109073 A1, May 17, 2007 | ||
| Int. Cl. H03H 9/00 (2006.01); H03H 9/54 (2006.01) | ||
| U.S. Cl. 333—133 [333/187; 333/193] | 17 Claims |
| 1. A filter comprising:
a series piezoelectric resonator part including at least one series piezoelectric resonator having a first electrode and a
second electrode, the series piezoelectric resonator being connected in series between an input terminal and an output terminal;
a parallel piezoelectric resonator part including at least two parallel piezoelectric resonators each having a first electrode
and a second electrode, the parallel piezoelectric resonators being connected, via the first electrodes, in parallel to the
series piezoelectric resonator and in a ladder configuration;
an inductor part including inductors provided to at least two of the parallel piezoelectric resonators, respectively, the
inductors each being connected between a ground and a respective one of the second electrodes of the parallel piezoelectric
resonators; and
an additional piezoelectric resonator part including at least one additional piezoelectric resonator having a first electrode
and a second electrode, the additional piezoelectric resonator being connected between any two second electrodes of the parallel
piezoelectric resonators having the inductors connected thereto.
|