| 摘要 |
Provided is a filter device capable of widening a band and increasing attenuation in an attenuation band separated from the pass band. A filter device (1) includes a first LC parallel resonance circuit (7) having a first inductance and connected between a line connecting an input terminal (2) and an output terminal (3) and a ground potential, a second LC parallel resonance circuit (9) having a second inductance and connected between the line and the ground potential, and at least one elastic wave resonator (21) that is connected between an end portion of the first LC parallel resonance circuit (7) and an end portion of the second LC parallel resonance circuit (9). In the filter device (1), attenuation-frequency characteristics of an LC filter using the first LC parallel resonance circuit (7), the second LC parallel resonance circuit (9), and a capacitive property of the at least one elastic wave resonator (21) and attenuation-frequency characteristics of the elastic wave resonator are used. |
