ANTENNA DUPLEXER AND COMMUNICATION DEVICE USING SAME

摘要

An antenna duplexer is provided with a transmitting-side filter and a receiving-side filter which are connected to an antenna terminal.  The passband of the transmitting-side filter is lower than the passband of the receiving-side filter.  The transmitting-side filter includes a first series resonator coupled to a first terminal, a second series resonator connected to the first series resonator at a first connection point, a first parallel resonator connected to the first end of the first series resonator, a second series resonator connected to the first connection point and connected to the first parallel resonator at a second connection point, a third parallel resonator connected to the first connection point, a fourth parallel resonator connected to the third parallel resonator at a third connection point, a first inductance element coupled to the second connection point and a ground, and a second inductance element coupled to the third connection point and the ground.  An attenuation pole is formed at a frequency lower than the passband of the transmitting-side filter by the first and second parallel resonators and the first inductance element.  An attenuation pole is formed at a frequency higher than the passband of the transmitting-side filter by the third and fourth parallel resonators and the second inductance element.  The inductance of the second inductance element is smaller than the inductance of the first inductance element.  In this antenna duplexer, the transmitting-side filter can fully suppress spurious due to harmonics contained in a transmission signal.