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:
Aug. 05, 1997
Filed:
Jan. 30, 1996
Philip Pak-Lin Kwan, Sunnyvale, CA (US);
Ali-Reza Baghai-Wadji, Mesa, AZ (US);
David Penunuri, Fountain Hills, AZ (US);
Motorola, Inc., Schaumburg, IL (US);
Abstract
A full duplex radio (10) having improved properties obtained by using surface acoustic wave (SAW) filters (92, 100, 100') having asymmetric frequency responses (76', 76', 140). The filters (92, 100, 100') are composed of series (50.sub.1, 50.sub.1 ') and parallel (50.sub.2, 50.sub.2 ') coupled SAW resonators. Asymmetry is obtained by altering the metallization thickness of either of the series (50.sub.1, 50.sub.1 ') or parallel (50.sub.2, 50.sub.2 ') resonators of each filter (92, 100, 100') to increase or decrease the SAW coupling coefficient of some of the resonators (50.sub.1, 50.sub.1 ', 50.sub.2, 50.sub.2 ') relative to the remainder of the resonators (50.sub.1, 50.sub.1 ', 50.sub.2, 50.sub.2 '). The filters (92, 100, 100') are desirably in pairs arranged with mirror image frequency asymmetry such that the steeper skirts (93, 95) of the frequency responses (76', 76', 140) are adjacent. Greater passband bandwidths (91', 91') can be obtained without adverse affect on transmitter and receiver isolation.