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:
Apr. 11, 2000
Filed:
Jan. 15, 1999
Susumu Yoshimoto, Tokyo, JP;
Yasushi Yamamoto, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
A surface acoustic wave filter includes IDTs on an input side and on an output side, the Inter Digital Transducers (IDTs) are formed by depositing a thin film made of aluminum and the like on a piezoelectric substrate made of crystal, and disposed on the substrate with a spacing interposed therebetween. The width of each electrode digit of each IDT is 1/4 of the wavelength of the surface acoustic wave during resonance. A reflection coefficient .epsilon. per electrode digit and the total number N of pairs of the electrode digits constituting the IDTs on the input side and on the output side are set to satisfy N.epsilon..gtoreq.0.55. Also, the aperture width W.lambda. of a surface acoustic wave transmission path, the center frequency of the filter f in units of Hertz , and the thickness of the electrode digits H in units of meters, are set to satisfy fH.ltoreq.-17.5W+210.