| 摘要 |
<p>To provide a tunable filter capable of magnifying a pass band width or increasing a frequency variable amount. A tunable filter (1) where a resonator circuit portion (S11, S12) is provided in at least one of a series arm connecting an input terminal (22) and an output terminal (23) to each other and a parallel arm connecting the series arm and a ground potential to each other, a first variable capacitor (C2, C3) is connected in series to the resonator circuit portion (S11, S12), and a second variable capacitor (CP1, CP2) is connected in parallel to the resonator circuit portion (S11, S12), wherein the resonator circuit portion includes a piezoelectric substrate (11) including LiNbO 3 or LiTaO 3 , an elastic wave resonator including an electrode (12) formed on the piezoelectric substrate (11), and a bandwidth extending inductance (Lx, Lx) connected to the elastic wave resonator.</p> |
