Abstract: An acoustic wave device includes an interdigital transducer electrode provided on a piezoelectric substrate, the interdigital transducer electrode includes first and second electrode fingers. The second electrode fingers are connected to an electric potential different from that of the first electrode fingers. A direction orthogonal or substantially orthogonal to a direction in which the first electrode fingers and the second electrode fingers extend is an acoustic wave propagation direction, the interdigital transducer electrode includes a first area centrally provided in the acoustic wave propagation direction, second areas provided on one side and another side of the first area in the acoustic wave propagation direction, and third areas each provided on a side of each of the second areas opposite to the first area in the acoustic wave propagation direction.

Abstract: A multiplexer includes a transmission-side filter connected to a common terminal and a transmission input terminal, and a reception-side filter connected to the common terminal and a reception output terminal, in which the transmission-side filter includes serial arm resonators, parallel arm resonators, and a parallel arm circuit. In an interdigital transducer electrode included in the serial arm resonator connected closest to the common terminal, an electrode finger pitch at a center portion in an arrangement direction of electrode fingers is maximum among electrode finger pitches of the interdigital transducer electrode, and electrode finger pitches at end portions in the arrangement direction are minimum among the electrode finger pitches of the interdigital transducer electrode.

Abstract: A multiplexer includes a transmission-side filter connected to a common terminal and a transmission input terminal, and a reception-side filter connected to the common terminal and a reception output terminal, in which the transmission-side filter includes serial arm resonators, parallel arm resonators, and a parallel arm circuit. In an interdigital transducer electrode included in the serial arm resonator connected closest to the common terminal, an electrode finger pitch at a center portion in an arrangement direction of electrode fingers is maximum among electrode finger pitches of the interdigital transducer electrode, and electrode finger pitches at end portions in the arrangement direction are minimum among the electrode finger pitches of the interdigital transducer electrode.

Abstract: An acoustic wave device includes an interdigital transducer electrode provided on a piezoelectric substrate, the interdigital transducer electrode includes first and second electrode fingers. The second electrode fingers are connected to an electric potential different from that of the first electrode fingers. A direction orthogonal or substantially orthogonal to a direction in which the first electrode fingers and the second electrode fingers extend is an acoustic wave propagation direction, the interdigital transducer electrode includes a first area centrally provided in the acoustic wave propagation direction, second areas provided on one side and another side of the first area in the acoustic wave propagation direction, and third areas each provided on a side of each of the second areas opposite to the first area in the acoustic wave propagation direction.

Abstract: A composite filter device includes a first filter and a plurality of second filters with different passbands. End portions of the first filter and the plurality of second filters are connected to a common connection. The first filter includes a piezoelectric substrate made of LiNbO3, an IDT electrode provided on the piezoelectric substrate, and a dielectric layer provided on the piezoelectric substrate so as to cover the IDT electrode. The first filter utilizes a fundamental wave of Rayleigh waves. The passband of the first filter is arranged in a frequency band that is lower than any of the passbands of the plurality of second filters.

Abstract: A composite filter device includes a first filter and a plurality of second filters with different passbands. End portions of the first filter and the plurality of second filters are connected to a common connection. The first filter includes a piezoelectric substrate made of LiNbO3, an IDT electrode provided on the piezoelectric substrate, and a dielectric layer provided on the piezoelectric substrate so as to cover the IDT electrode. The first filter utilizes a fundamental wave of Rayleigh waves. The passband of the first filter is arranged in a frequency band that is lower than any of the passbands of the plurality of second filters.