Patent ID: 8410869
Filing Date: 2013-04-02
Classification: H03H

Abstract:
1. An elastic-wave filter device having a pass band and a stop band at frequencies higher than the pass band, the elastic-wave filter device comprising: an input terminal; an output terminal; a band-pass filter connected in series between the input terminal and the output terminal; and a first band-eliminate filter connected in series between the input terminal and the output terminal; wherein the first band-eliminate filter includes a series arm connected in series between the input terminal and the output terminal, at least one inductor connected in series in the series arm, a plurality of parallel arms connected between the series arm and a ground potential, and a plurality of parallel-arm resonators in the respective plurality of parallel arms; the plurality of parallel-arm resonators include a first parallel-arm resonator having a first resonance frequency in the stop band and a second parallel-arm resonator having a second resonance frequency in the stop band, the second resonance frequency being higher than the first resonance frequency; and an impedance value of the first parallel-arm resonator is larger than an impedance value of the second parallel-arm resonator.