Abstract: An acoustic wave resonator includes: a piezoelectric substrate; and an interdigital transducer (IDT) located on the piezoelectric substrate, the IDT including a pair of comb-shaped electrodes having a plurality of electrode fingers and a bus bar to which the plurality of electrode fingers are coupled, the IDT having: a first region in which a pitch of electrode fingers is substantially constant; a second region in which a pitch of electrode fingers decreases at closer distances to an outer side; and a third region in which a pitch of electrode fingers increases at closer distances to an outer side, the second region being located outside the first region in an arrangement direction of the plurality of electrode fingers, and the third region being located outside the second region in the arrangement direction.

Abstract: An acoustic wave resonator includes: a piezoelectric substrate; and an interdigital transducer (IDT) located on the piezoelectric substrate, the IDT including a pair of comb-shaped electrodes having a plurality of electrode fingers and a bus bar to which the plurality of electrode fingers are coupled, the IDT having: a first region in which a pitch of electrode fingers is substantially constant; a second region in which a pitch of electrode fingers decreases at closer distances to an outer side; and a third region in which a pitch of electrode fingers increases at closer distances to an outer side, the second region being located outside the first region in an arrangement direction of the plurality of electrode fingers, and the third region being located outside the second region in the arrangement direction.

Abstract: An acoustic wave filter includes: one or more series resonators connected in series between an input terminal and an output terminal; and parallel resonators connected in parallel between the input terminal and the output terminal and formed of piezoelectric thin film resonators, wherein each of at least two resonators of the parallel resonators includes an additional film having island-shaped patterns or aperture patterns formed at equal pitch intervals in a resonance region in which a lower electrode and an upper electrode face each other across a piezoelectric film, and a pitch interval of the island-shaped patterns or the aperture patterns in the additional film included in one of the at least two resonators differs from a pitch interval of the island-shaped patterns or the aperture patterns in the additional film included in another one of the at least two resonators.

Abstract: An acoustic wave filter includes: one or more series resonators connected in series between an input terminal and an output terminal; and parallel resonators connected in parallel between the input terminal and the output terminal and formed of piezoelectric thin film resonators, wherein each of at least two resonators of the parallel resonators includes an additional film having island-shaped patterns or aperture patterns formed at equal pitch intervals in a resonance region in which a lower electrode and an upper electrode face each other across a piezoelectric film, and a pitch interval of the island-shaped patterns or the aperture patterns in the additional film included in one of the at least two resonators differs from a pitch interval of the island-shaped patterns or the aperture patterns in the additional film included in another one of the at least two resonators.

Abstract: A filter includes: a filter circuit connected between a first terminal and a second terminal; and a matching circuit connected between the filter circuit and the second terminal, wherein an impedance viewed from the second terminal toward the matching circuit is less than an impedance viewed from a node between the filter circuit and the matching circuit toward the filter circuit.

Abstract: A filter includes: a filter circuit connected between a first terminal and a second terminal; and a matching circuit connected between the filter circuit and the second terminal, wherein an impedance viewed from the second terminal toward the matching circuit is less than an impedance viewed from a node between the filter circuit and the matching circuit toward the filter circuit.