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:
Nov. 30, 1999
Filed:
Oct. 07, 1997
Yutaka Tada, Kanazawa, JP;
Abstract
An elastic surface acoustic wave filter device provides balanced operation with a neutral terminal kept at a ground potential and is adaptable for any system of unbalanced input-to-balanced output or balanced input-to-unbalanced output even with an input and an output having a different characteristic impedance. A first elastic surface acoustic wave filter having a first predetermined phase is connected in a cascade arrangement to a second elastic surface acoustic wave filter having a phase that is different by about 180 degrees from the first predetermined phase to form a first set of cascaded elastic surface acoustic wave filters. A third elastic surface acoustic wave filter having the first predetermined phase is connected in a cascade arrangement to a fourth elastic surface acoustic wave filter having the predetermined phase to form a second set of cascaded elastic surface acoustic wave filters. One of input/output terminals of the first set of cascaded elastic surface acoustic wave filters and one of input/output terminals of the second set of cascaded elastic surface acoustic wave filters are electrically connected in parallel to an unbalanced input/output terminal. The other of input/output terminals of the first set of cascaded elastic surface acoustic wave filters and the other of input/output terminals of the second set of cascaded elastic surface acoustic wave filters are electrically connected in series to balanced input/output terminals.