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AssigneeMotorola, Inc.
InventorsDonald Eugene Allen, Philip Pak-Lin Kwan, David Patrick Stumbo
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A full duplex radio (10) having improved properties is obtained by using asymmetric surface acoustic wave (SAW) filters (70, 92, 100, 100', 112). The filters (70, 92, 100, 100', 112) 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 covering either of the series (50.sub.1, 50.sub.1 ') or parallel (50.sub.2, 50.sub.2 ') resonators of each filter (70, 92, 100, 100', 112) with a dielectric layer (96) to increase the SAW coupling coefficient (Cs, Cp) of the covered resonators (50.sub.1 ', 50.sub.2 ') relative to the uncovered resonators (50.sub.1, 50.sub.2). The filters (70, 92, 100, 100', 112) are desirably in pairs arranged with mirror image frequency asymmetry such that the steeper skirts (87, 79) of the frequency response (91', 91") are adjacent. Greater pass-band bandwidths (77, 77', 77") can be obtained without adverse affect on transmitter and receiver isolation.
A filter device utilizing surface acoustic wave (SAW) resonators comprising:
A surface acoustic wave (SAW) filter device on a common substrate, said SAW filter device comprising:
A radio incorporating surface acoustic wave filters comprising:
A radio incorporating surface acoustic wave (SAW) resonators, said radio comprising:
Dependencies are inferred from the claim text.