The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 06, 2005
Filed:
Jun. 26, 2002
Akio Tsunekawa, Osaka, JP;
Shunichi Seki, Hyogo, JP;
Shinobu Nakaya, Osaka, JP;
Hiroyuki Nakamura, Osaka, JP;
Toru Yamada, Osaka, JP;
Akio Tsunekawa, Osaka, JP;
Shunichi Seki, Hyogo, JP;
Shinobu Nakaya, Osaka, JP;
Hiroyuki Nakamura, Osaka, JP;
Toru Yamada, Osaka, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
A longitudinally coupled surface acoustic wave filter includes a first, second and third IDT electrodes and a first and second reflector electrodes on a piezoelectric substrate. The IDT electrodes each include a primary excitation region having λ/2 electrode finger pitches, where λ is the wavelength of a surface acoustic wave. The primary excitation region is phase-shifted by a certain amount in accordance with a desired passband frequency response. The IDT electrodes further include a plurality of secondary excitation regions each having electrode finger pitches different from the λ/2 pitches. All of the electrode finger pitches of the surface acoustic wave filter thus range from 0.8λ/2 to 1.2λ/2, so that a loss increase caused by discontinuity between the IDT electrodes is prevented.