Patent ID: 8106725
Filing Date: 2012-01-31
Classification: H03H

Abstract:
1. An acoustic wave filter device comprising: an unbalanced terminal; first and second balanced terminals; longitudinally coupled resonator-acoustic wave filters that are connected between the unbalanced terminal and the first balanced terminal and between the unbalanced terminal and the second balanced terminal and that have a balanced-unbalanced conversion function; a first parallel resonator connected between the first balanced terminal and a ground potential; and a second parallel resonator connected between the second balanced terminal and the ground potential; wherein the electrostatic capacitance of the first parallel resonator is different from that of the second parallel resonator; and among the first and second parallel resonators, a wavelength of the parallel resonator having a relatively small electrostatic capacitance is shorter than that of the parallel resonator having a relatively large electrostatic capacitance.