ACOUSTIC WAVE FILTER DEVICE

摘要

The disclosed acoustic wave filter device provided with a bandpass filter and a band-reject filter unit connected to the bandpass filter unit reduces insertion loss in the passband, and increases attenuation in the stopband. The acoustic wave filter (1), which has a passband and a higher-frequency stopband, is provided with a bandpass filter unit (10) and a first band-reject filter unit (20) connected in series between an input terminal (2) and an output terminal (3). A first parallel arm resonator (P1) of the first band-reject filter unit (20) has a resonance frequency in the stopband. A second parallel arm resonator (P2) has a resonance frequency in the stopband that is higher than that of the first parallel arm resonator (P1). The impedance of the first parallel arm resonator (P1) is greater than that of the second parallel arm resonator (P2).