Tunable filter

Abstract

A tunable filter that is capable of magnifying a pass band width or increasing a frequency variable amount includes a resonator circuit portion provided in at least one of a series arm connecting an input terminal and an output terminal to each other and a parallel arm connecting the series arm and a ground potential to each other, a first variable capacitor is connected in series to the resonator circuit portion and a second variable capacitor is connected in parallel to the resonator circuit portion. The resonator circuit portion includes a piezoelectric substrate including LiNbO3 or LiTaO3, an elastic wave resonator including an electrode located on the piezoelectric substrate, and a bandwidth extending inductance Lx, Lx connected to the elastic wave resonator.

Dependencies are inferred from the claim text.