Murata Manufacturing Co., Ltd.

Kentaro Nakamura

Noriyoshi Ota

Syunsuke Kido

Shinichi Okada

An acoustic wave device includes a substrate including a piezoelectric layer, first and second resonators on the substrate, and a shared reflector. The second resonator is located on the substrate adjacent to the first resonator and has different frequency characteristics than the first resonator. The shared reflector is located on the substrate between the first resonator and the second resonator and is a reflector for both the first resonator and the second resonator. The first resonator includes a first interdigital transducer electrode with electrode fingers positioned with a first pitch. The second resonator includes a second interdigital transducer electrode with electrode fingers positioned with a second pitch. A lower limit frequency of a stop band of the shared reflector is between a lower limit frequency of a stop band of the first resonator and a lower limit frequency of a stop band of the second resonator. An upper limit frequency of the stop band of the shared reflector is between an upper limit frequency of the stop band of the first resonator and an upper limit frequency of the stop band of the second resonator.

Acoustic wave device, and ladder filter including the same

An acoustic wave device includes a substrate, a first resonator, a second resonator, and a shared reflector. The second resonator is adjacent to the first resonator and has different frequency characteristics different than the first resonator. The first resonator includes a first interdigital transducer electrode. The second resonator includes a second interdigital transducer electrode. The shared reflector has frequency characteristics that are the same as both frequency characteristics of the first resonator and frequency characteristics of the second resonator or between the frequency characteristics of the first resonator and the frequency characteristics of the second resonator. a higher-order mode frequency of the first resonator and a higher-order mode frequency of the second resonator coincides. When the number of electrode fingers of the shared reflector is even, an electrode finger facing the shared reflector in the first interdigital transducer electrode and an electrode finger facing the shared reflector in the second interdigital transducer electrode have the same polarity. When the number of electrode fingers of the shared reflector is odd, an electrode finger facing the shared reflector in the first interdigital transducer electrode and an electrode finger facing the shared reflector in the second interdigital transducer electrode have opposite polarities.

A filter includes series resonators on a signal path, each of the series resonator including an IDT electrode that includes first electrode fingers each including a variant portion, second electrode fingers each including no variant portion, or both the first electrode fingers and the second electrode fingers, in the IDT electrode of one or more series resonators of the series resonators, a direction connecting other-side end portions of electrode fingers crosses an acoustic wave propagation direction, the IDT electrode includes the first electrode fingers, a first portion of an IDT electrode of another series resonator centrally located in the acoustic wave propagation direction, includes only the first electrode fingers, and a second portion and a third portion on two sides of the first portion each include only the second electrode fingers.

Filter, multiplexer, radio frequency front-end circuit, and communication device

A filter includes series resonators in a signal path. An IDT electrode included in the series resonators includes at least either first electrode fingers including variant portions or second electrode fingers not including variant portions. In the IDT electrode included in one or more series resonators of the series resonators, a direction that connects the respective other ends of a plurality of electrode fingers intersects an acoustic wave propagation direction. In a first portion and a second portion of the IDT electrode, the first and second electrode fingers are arranged in a predetermined order.

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Nagaokakyo, Japan

Kentaro Nakamura