An elastic wave device includes an IDT electrode disposed on a piezoelectric substrate and including first and second electrode fingers that are interdigitated. A region where the first and second electrode fingers overlap each other as seen in a direction of propagation of elastic waves is an excitation region. Edge portions where an acoustic velocity is lower than an acoustic velocity in a central portion are disposed on opposite sides of a central portion in the excitation region. A first busbar and second busbar include inner busbar portions, central busbar portions, and outer busbar portions. First and second offset electrode fingers extend from the inner busbar portions toward the leading ends of the second electrode fingers or first electrode fingers.

The present invention relates to a heterostructure, in particular, a piezoelectric structure, comprising a cover layer, in particular, a layer of piezoelectric material, the material of the cover layer having a first coefficient of thermal expansion, assembled to a support substrate, the support substrate having a second coefficient of thermal expansion substantially different from the first coefficient of thermal expansion, at an interface wherein the cover layer comprises at least a recess extending from the interface into the cover layer, and its method of fabrication.

A surface acoustic wave filter includes a longitudinal mode resonator type first filter portion, a longitudinal mode resonator type second filter portion, an input terminal, and an output terminal. Assuming a wavelength of a frequency propagating through the first filter portion is defined as , a distance between a center of a width of an electrode finger closest to the output side IDT electrode and a center of a width of an electrode finger closest to the input side IDT electrode is equal to or more than 0.57. The electrode finger closest to the output side IDT electrode is closest among electrode fingers that constitute the input side IDT electrode and are arranged in the propagation direction, and the electrode finger closest to the input side IDT electrode is closest among electrode fingers that constitute the output side IDT electrode and are arranged in the propagation direction.

The present invention relates to a heterostructure, in particular, a piezoelectric structure, comprising a cover layer, in particular, a layer of piezoelectric material, the material of the cover layer having a first coefficient of thermal expansion, assembled to a support substrate, the support substrate having a second coefficient of thermal expansion substantially different from the first coefficient of thermal expansion, at an interface wherein the cover layer comprises at least a recess extending from the interface into the cover layer, and its method of fabrication.

A multiplexer includes a transmission-side filter electrically connected to a common terminal and a transmission input terminal, and a transmission-side filter electrically connected to the common terminal and a transmission input terminal. The transmission-side filter includes a plurality of series arm resonators and a plurality of parallel arm resonators. Capacitance elements are respectively electrically connected in parallel to the series arm resonator and the parallel arm resonator, which are connected most proximately to the common terminal. IDT electrodes of a series arm resonator and a parallel arm resonator connected most proximately to the common terminal do not include a thinning electrode, and others of the series arm resonators and the parallel arm resonators include thinning electrodes.

An elastic wave device includes a piezoelectric substrate and IDT electrodes including first and second busbars and first and second electrode fingers. An intersection of the IDT electrodes includes a center region, and low-acoustic-velocity sections at both end portions of the center region in the direction in which the electrode fingers extend in the center region, sections in which the acoustic velocity is lower than in the center region. The length of the gap between the edge of the first electrode fingers and the second busbar and the length of the gap between the edge of the second electrode fingers and the first busbar are about 0.62 or more and about 0.98 or less, where denotes the wavelength, which is determined by the finger pitch of the IDT electrodes.

An acoustic wave filter device includes a piezoelectric layer, a high-acoustic-velocity member, a low-acoustic-velocity film between the high-acoustic-velocity member and the piezoelectric layer, and first and second IDT electrodes on the piezoelectric layer to define acoustic wave resonators. An acoustic wave resonator of a series-arm resonator portion closest to an antenna end and/or an acoustic wave resonator of a parallel-arm resonator portion closest to the antenna end includes the first IDT electrode including first and second electrode fingers, and the remaining acoustic wave resonators include the second IDT electrode including third and fourth electrode fingers. In the first IDT electrode, a central area, first and second low-acoustic-velocity areas, and first and second high-acoustic-velocity areas extend along a direction perpendicular or substantially perpendicular to an acoustic wave propagating direction. First and second envelopes connecting the tips of the third and fourth electrode fingers of the second IDT electrode are inclined.

An acoustic wave filter includes a piezoelectric substrate, first and second input-output terminals, and a longitudinally coupled resonator unit in a path connecting the first and second input-output terminals to each other, and the resonator unit includes five or more interdigital transducer electrodes aligned in an acoustic wave propagation direction, the IDT electrodes include a center IDT electrode at the center in the propagation direction and first and second IDT electrodes at symmetric or substantially symmetric positions in the propagation direction with respect to the center IDT electrode, each of the first and second IDT electrodes includes a main pitch portion and a pair of narrow-pitch portions provided between the main pitch portion and both ends of the IDT electrode in the propagation direction, and the first and second IDT electrodes differ from each other in the number of electrode fingers of the main pitch portion.

A filter circuit has a first frequency band as a pass band and a second frequency band as an attenuation band. The filter circuit includes a 90-degree hybrid coupler, a first filter that is connected to the 90-degree hybrid coupler and has the first frequency band as a pass band, and a second filter that is connected to the 90-degree hybrid coupler and has the second frequency band as a pass band. The second filter includes a first inductor, a resonant circuit, and a second inductor connected in series in this order, a first capacitive element connected between a node on a signal path connecting the first inductor and the resonant circuit and a ground electrode, and a second capacitive element connected between a node on a signal path connecting the second inductor and the resonant circuit and a ground electrode.

An acoustic wave device includes a support substrate, a silicon nitride film stacked on the support substrate, a silicon oxide film stacked on the silicon nitride film, a piezoelectric body stacked on the silicon oxide film and made of lithium tantalite, and an IDT electrode provided on one main surface of the piezoelectric body. For a wavelength normalized film thickness of the piezoelectric body, an Euler angle of the piezoelectric body, a wavelength normalized film thickness of the silicon nitride film, a wavelength normalized film thickness of the silicon oxide film, and a wavelength normalized film thickness of the IDT electrode, values are set so that at least one of a response intensity of a first higher order mode, corresponding to the response intensity of a second higher order mode, and of a response intensity of a third higher mode is greater than about 2.4.