| 摘要 |
Provided is a filter device in which the amount of attenuation can be increased in an attenuation band separated from a wide band and a pass band. The filter device (1) is provided with: a first LC parallel resonant circuit (7), which contains a first inductor, connected between a line connecting an input terminal (2) and an output terminal (3), and a ground potential; a second LC parallel resonant circuit (9), which contains a second inductor, connected between the line and ground potential; and at least one acoustic wave resonator (21) that is connected between a terminal of the first LC parallel resonant circuit (7), and a terminal of the second LC parallel resonant circuit (9). The filter device (1) uses: the attenuation frequency characteristics as an LC filter, which uses the first LC parallel resonant circuit (7), the second LC parallel resonant circuit (9) and the capacitance of the at least one acoustic wave resonator; and the attenuation frequency characteristics of the acoustic wave resonator. |
