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:
May. 18, 1999
Filed:
Dec. 18, 1997
Applicant:
Inventors:
Hisanori Ehara, Tokyo, JP;
Kazushige Noguchi, Tokyo, JP;
Hajime Shimamura, Tokyo, JP;
Yoshio Okada, Tokyo, JP;
Tomokazu Komazaki, Tokyo, JP;
Assignee:
Oki Electric Industry Co., Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H03H / ;
U.S. Cl.
CPC ...
333193 ; 333133 ; 333195 ;
Abstract
A surface-acoustic-wave filter couples a two-port surface-acoustic-wave resonator filter circuit coupled in parallel or in series with a two-port impedance circuit. The two-port impedance circuit has an impedance that creates a pole of attenuation, by making the open-circuit impedance of the surface-acoustic-wave filter equal to the short-circuit impedance. High attenuation over a wide range of stopband frequencies is obtained in this way, combined with steep roll-off between the passband and stopband.