Patent ID: 6975180
Filing Date: 2005-12-13
Classification: H03H

Abstract:
1. An antenna duplexer, comprising: an antenna terminal; a reception filter connected to said antenna terminal; a transmission filter connected to said antenna terminal; and a first phase circuit provided between said antenna terminal and said reception filter and/or a second phase circuit provided between said antenna terminal and said transmission filter, wherein said reception filter is a surface acoustic wave filter, comprising: at least one piezoelectric substrate; at least one surface acoustic wave resonator formed on said piezoelectric substrate; and a longitudinal coupled mode type surface acoustic wave filter formed on said piezoelectric substrate, wherein said surface acoustic wave resonator and said longitudinal coupled mode type surface acoustic wave filter are cascaded together, wherein said surface acoustic wave resonator is also connected to at least one inductor having one end grounded, and wherein an attenuation band of said at least one surface acoustic wave resonator is apart from a pass band of said longitudinal coupled mode type surface acoustic wave filter in the direction of higher frequencies.