Patent ID: 6313715
Filing Date: 2001-11-06
Classification: H03H

Abstract:
A surface acoustic wave (SAW) duplexer operating with surface acoustic waves, comprising:a chip made of lithium tantalate, including:a transmission path containing a transmission SAW filter having an impedance;a reception path containing a reception SAW filter having an impedance;a transformation network having a series capacitance being an interdigital converter disposed in one of said transmission path and said reception path, said interdigital converter having a mid-frequency greater by a factor of at least 1.05 than a mid-frequency of a passband of said one of said transmission SAW filter and said reception SAW filter switched in series, said transformation network transforming said impedance of one of said transmission SAW filter and said reception SAW filter in a passband of the other of said transmission SAW filter and said reception SAW filter to a high-impedance area; andan antenna connected to said transmission path and said reception path, and said series capacitance disposed between said antenna and one of said transmission path and said reception path.