Abstract: An acoustic wave device includes a support substrate, a piezoelectric layer on the support substrate and including first and second principal surfaces, first and second IDT electrodes respectively on the first and second principal surfaces, and a dielectric film at least provided at one of a position between the first principal surface and the first IDT electrode, and a position between the second principal surface and the second IDT electrode. Each of the dielectric film and the piezoelectric layer includes one of Li, Ta, and O or Li, Nb, and O. At least one of a polarization direction, an element included in a material, and a composition of the material is different between the dielectric film and the piezoelectric layer.

Abstract: An acoustic wave device includes an Interdigital Transducer (IDT) electrode on a first main surface of a piezoelectric layer, a conductive material layer on a second main surface of the piezoelectric layer, and a dielectric layer provided between the piezoelectric layer and the conductive material layer. When a film thickness of the piezoelectric layer is represented as Tp[?] and a film thickness of the dielectric layer is represented as Td[?], the Formula (1) is satisfied or Td=0, where ? is a wavelength determined by an electrode finger pitch of the IDT electrode, and Tp[?]?about 0.025: Td[?]??2.369×(Tp[?])4 +2.721×(Tp[?])3 ?1.049×(Tp[?])2 +0.076×(Tp[?]) +0.095??Formula (1).

Abstract: An acoustic wave device includes a substrate, an interdigital transducer electrode including electrode fingers on a main surface of the substrate, and a protection film covering the main surface of the substrate, and side surfaces and upper surfaces of the electrode fingers. The protection film includes a portion covering the main surface of the substrate, an intermediate portion between two of the electrode fingers adjacent to each other, and a vicinity portion of the electrode fingers. The intermediate portion is thicker than the vicinity portion.

Abstract: An acoustic wave filter includes a series-arm resonator, a first parallel-arm resonator, and a second parallel-arm resonator. The series-arm resonator is disposed on a path connecting first and second input/output terminals. The first parallel-arm resonator is disposed on a path that connects ground with a node, which is located on a path connecting the series-arm resonator with the first input/output terminal. The second parallel-arm resonator is disposed on a path that connects ground with a node, which is located on a path connecting the series-arm resonator with the second input/output terminal. The parallel-arm resonator has a resonant frequency lower than the resonant frequency of the second parallel-arm resonator. The first parallel-arm resonator has an anti-resonant frequency higher than the anti-resonant frequency of the second parallel-arm resonator. The second parallel-arm resonator has the highest resonant frequency of all the parallel-arm resonators.

Abstract: An acoustic wave resonator includes an IDT electrode that is on or above a piezoelectric plate and includes a periodic withdrawal weighted portion in each of a plurality of regions for at least two or more periods in an acoustic wave propagation direction. A periodic withdrawal weighted portion in at least one of the regions is different from a periodic withdrawal weighted portion in at least one of the other regions.

Abstract: A surface acoustic wave element includes a substrate including a LiNbO3 piezoelectric single crystal, a first dielectric layer provided on the substrate, and an IDT electrode provided on the first dielectric layer, and propagates a high-frequency signal on the substrate using a Rayleigh wave.

Abstract: An acoustic wave device includes a piezoelectric substrate including a piezoelectric layer made of lithium tantalate, an IDT electrode on the piezoelectric substrate, and a pair of reflectors on both sides of the IDT electrode on the piezoelectric substrate in an acoustic wave propagation direction. SH waves are used as a principal mode. The IDT electrode includes electrode fingers and the pair of reflectors each including electrode fingers. When a length along a direction orthogonal to a direction in which the electrode fingers extend is a width, each of the reflectors includes first and second electrode fingers having different widths. Four consecutive electrode fingers, which are any four of the electrode fingers of each of the reflectors, include both of the first and second electrode fingers and distances between centers of the four consecutive electrode fingers are equal or substantially equal.

Abstract: An acoustic wave device includes a support substrate, a low-acoustic-velocity film on the support substrate, a piezoelectric layer on the low-acoustic-velocity film, an IDT electrode on the piezoelectric layer, and a high-acoustic-velocity film between the support substrate and the low-acoustic-velocity film. An acoustic velocity of a bulk wave propagating through the low-acoustic-velocity film is lower than an acoustic velocity of a bulk wave propagating through the piezoelectric layer. An acoustic velocity of a bulk wave propagating though the high-acoustic-velocity film is higher than an acoustic velocity of an acoustic wave propagating through the piezoelectric layer. Adhesion between the low-acoustic-velocity film and the support substrate is higher than adhesion between the high-acoustic-velocity film and the support substrate.

Abstract: An acoustic wave device includes an electrode finger on a principal surface of a piezoelectric substrate and extending in a Y-axis direction. In the acoustic wave device, an acoustic wave velocity is distributed in an order of an intermediate velocity, a low velocity, and a high velocity from a center of the electrode finger toward outer side portions in the Y-axis direction. The acoustic wave device further includes a dielectric between the piezoelectric substrate and a tip-end portion of the electrode finger. An end surface of the dielectric in the Y-axis direction includes first and second side surfaces. A tilt angle of the first side surface is smaller than a tilt angle of the second side surface.

Abstract: An elastic wave device includes a piezoelectric substrate, elastic wave resonators on or in the piezoelectric substrate, and a dielectric film disposed on the piezoelectric substrate and covering the elastic wave resonators. The elastic wave resonators includes respective IDT electrodes on the piezoelectric substrate. When a wavelength specified by an electrode finger pitch of the IDT electrode is denoted as ?, at least two of the elastic wave resonators have the different wavelengths. In two of the elastic wave resonators having different wavelengths, a film thickness of the IDT electrode in the elastic wave resonator having the longer wavelength is not greater than that of the IDT electrode in the elastic wave resonator having the shorter wavelength. Film thicknesses of the IDT electrodes in at least two of the elastic wave resonators are different from each other. The elastic wave device utilizes a Rayleigh wave.

Abstract: A filter device includes first and second filters respectively having first and second passbands, the second passband being in a frequency range higher than the first passband. The first and second filters are commonly connected to a common terminal. In the first filter, multiple parallel arm resonators define a parallel connection unit in which the parallel arm resonators are connected in parallel with no serial arm resonators interposed therebetween. The parallel arm resonators in the parallel connection unit include first and second parallel arm resonators having anti-resonant frequencies different from each other. In combined impedance-frequency characteristics of the parallel arm resonators in the parallel connection unit, at least one anti-resonant frequency other than a highest anti-resonant frequency is equal to or higher than 2f1min?f2min and equal to or lower than 2f1max?f2max.

Abstract: An acoustic wave device includes a substrate, an interdigital transducer electrode including electrode fingers on a main surface of the substrate, and a protection film covering the main surface of the substrate, and side surfaces and upper surfaces of the electrode fingers. The protection film includes a portion covering the main surface of the substrate, an intermediate portion between two of the electrode fingers adjacent to each other, and a vicinity portion of the electrode fingers. The intermediate portion is thicker than the vicinity portion.

Abstract: An elastic wave device includes first and second IDT electrodes provided over a principal surface of a piezoelectric substrate. The first IDT electrode is provided directly on a principal surface of the piezoelectric substrate and the second IDT electrode is provided over the principal surface with a first dielectric layer interposed therebetween. A second dielectric layer extends to upper portions of the first and second IDT electrodes. A wiring electrode passes over the second dielectric layer and extends to the upper portions of the first and second IDT electrodes. Respective angles between first and second side surfaces of the second dielectric layer and the principal surface of the piezoelectric substrate are smaller than an angle between a side surface of the first dielectric layer and the principal surface of the piezoelectric substrate.

Abstract: An acoustic wave device includes a support substrate including silicon, a piezoelectric layer in which a rotated Y-cut X-propagation lithium tantalate is included, and an IDT electrode. A film thickness of the piezoelectric layer is less than or equal to about 1?. When ?111 is an angle between a directional vector k111, and a direction of silicon and n is an arbitrary integer, the angle ?111 is in a range of about 0°+120°×n??111?45°+120°×n or in a range of about 75°+120°×n??111?120°+120°×n when the IDT electrode is on a positive surface of the piezoelectric layer and the angle ?111 is in a range of about 15°+120°×n??111?105°+120°×n when the IDT electrode is on the negative surface of the piezoelectric layer.

Abstract: An acoustic wave device includes a support substrate having a central region and a surrounding region located around the central region, a silicon oxide film that is located in the central region directly or indirectly and that has a side surface, a piezoelectric layer that is provided on the silicon oxide film and that has a first principal surface and a second principal surface, an excitation electrode provided on at least one of the first principal surface and the second principal surface, a cover film provided to cover the entire side surface of the silicon oxide film, a resin layer that is provided in the surrounding region and that is provided to cover the side surface of the silicon oxide film from above the cover film, and a wiring electrode that is electrically connected to the excitation electrode and that extends from the piezoelectric layer to the resin layer.

Abstract: An acoustic wave device includes a piezoelectric substrate including a piezoelectric layer made of lithium tantalate, an IDT electrode on the piezoelectric substrate, and a pair of reflectors on both sides of the IDT electrode on the piezoelectric substrate in an acoustic wave propagation direction. SH waves are used as a principal mode. The IDT electrode includes electrode fingers and the pair of reflectors each including electrode fingers. When a length along a direction orthogonal to a direction in which the electrode fingers extend is a width, each of the reflectors includes first and second electrode fingers having different widths. Four consecutive electrode fingers, which are any four of the electrode fingers of each of the reflectors, include both of the first and second electrode fingers and distances between centers of the four consecutive electrode fingers are equal or substantially equal.

Abstract: An acoustic wave filter includes a series-arm resonator, a first parallel-arm resonator, and a second parallel-arm resonator. The series-arm resonator is disposed on a path connecting first and second input/output terminals. The first parallel-arm resonator is disposed on a path that connects ground with a node, which is located on a path connecting the series-arm resonator with the first input/output terminal. The second parallel-arm resonator is disposed on a path that connects ground with a node, which is located on a path connecting the series-arm resonator with the second input/output terminal. The parallel-arm resonator has a resonant frequency lower than the resonant frequency of the second parallel-arm resonator. The first parallel-arm resonator has an anti-resonant frequency higher than the anti-resonant frequency of the second parallel-arm resonator. The second parallel-arm resonator has the highest resonant frequency of all the parallel-arm resonators.

Abstract: An acoustic wave filter includes a series-arm resonator, a first parallel-arm resonator, and a second parallel-arm resonator. The series-arm resonator is disposed on a path connecting first and second input/output terminals. The first parallel-arm resonator is disposed on a path that connects ground with a node, which is located on a path connecting the series-arm resonator with the first input/output terminal. The second parallel-arm resonator is disposed on a path that connects ground with a node, which is located on a path connecting the series-arm resonator with the second input/output terminal. The parallel-arm resonator has a resonant frequency lower than the resonant frequency of the second parallel-arm resonator. The first parallel-arm resonator has an anti-resonant frequency higher than the anti-resonant frequency of the second parallel-arm resonator. The second parallel-arm resonator has the highest resonant frequency of all the parallel-arm resonators.

Abstract: An acoustic wave resonator includes an IDT electrode that is on or above a piezoelectric plate and includes a periodic withdrawal weighted portion in each of a plurality of regions for at least two or more periods in an acoustic wave propagation direction. A periodic withdrawal weighted portion in at least one of the regions is different from a periodic withdrawal weighted portion in at least one of the other regions.

Abstract: An acoustic wave device includes a support substrate having a central region and a surrounding region located around the central region, a silicon oxide film that is located in the central region directly or indirectly and that has a side surface, a piezoelectric layer that is provided on the silicon oxide film and that has a first principal surface and a second principal surface, an excitation electrode provided on at least one of the first principal surface and the second principal surface, a cover film provided to cover the entire side surface of the silicon oxide film, a resin layer that is provided in the surrounding region and that is provided to cover the side surface of the silicon oxide film from above the cover film, and a wiring electrode that is electrically connected to the excitation electrode and that extends from the piezoelectric layer to the resin layer.