Abstract: An acoustic wave device includes a piezoelectric substrate in which a reverse-velocity surface is convex and an IDT electrode on the piezoelectric substrate. When an acoustic wave propagation direction is a first direction and a direction perpendicular or substantially perpendicular to the first direction is a second direction, the portion of the IDT electrode where first and second electrode fingers overlap in the first direction is a crossing region. The crossing region includes a center region centrally located in the second direction and a first and second edge regions located on two sides of the center region. Recesses 17 and 18 are respectively provided in portions of the piezoelectric substrate located in the first and second edge regions between the portions where the first and second electrode fingers are provided.

Abstract: An acoustic wave device includes a support substrate, a first high acoustic velocity film on the support substrate, a low acoustic velocity film on the first high acoustic velocity film, a second high acoustic velocity film on the low acoustic velocity film, a piezoelectric layer on the second high acoustic velocity film, and an IDT on the piezoelectric layer. Bulk waves propagate in the low acoustic velocity film more slowly than bulk waves propagate in the piezoelectric layer, bulk waves propagate in the first high acoustic velocity film faster than acoustic waves propagate on the piezoelectric layer, and bulk waves propagate in the second high acoustic velocity film faster than or as fast as bulk waves propagate in the first high acoustic velocity film.

Abstract: An acoustic wave device includes a (111)-oriented silicon substrate, a silicon nitride layer, a silicon oxide layer, a lithium tantalate layer, and an IDT electrode on the lithium tantalate layer. When the wavelength determined by the electrode finger pitch of the IDT electrode is ?, the thickness of the silicon nitride layer, SiN [?], the thickness of the silicon oxide layer, SiO2 [?], the thickness of the lithium tantalate layer, LT [?], and one of the Euler angles of the lithium tantalate layer, LT? [deg.], are thicknesses and an angle in ranges in which the phase of a first higher-order mode is about ?20° or less.

Abstract: A first filter of a multiplexer includes a ladder filter structure of acoustic wave resonators. An imaginary line obtained by connecting second ends of electrode fingers included in one comb-shaped electrode among a pair of comb-shaped electrodes of each resonator intersects a reference line that is a straight line extending in an acoustic wave propagation direction. When an angle defined by the reference line and the imaginary line of a first series resonator is represented by a first slant angle, an angle defined by the reference line and the imaginary line of a parallel resonator is represented by a second slant angle, and an angle defined by the reference line and the imaginary line of acoustic wave resonators is represented by a third slant angle, at least one of the first slant angle and the second slant angle is larger than the third slant angle.

Abstract: An acoustic wave device includes a piezoelectric substrate with a reverse-velocity surface having an ellipse shape, an IDT electrode on the piezoelectric substrate, and a dielectric film on the piezoelectric substrate and covering the IDT electrode. The acoustic wave device utilizes a Love wave. The IDT electrode includes an intersecting region in which first electrode fingers and second electrode fingers are interdigitated. The intersecting region includes a central region, a first edge region and a second edge region located at both ends of the central region. When x (%) denotes a wavelength-normalized film thickness of the IDT electrode and y (g/cm3) denotes an electrode density of the IDT electrode, the wavelength-normalized film x is set at a value not less than x that satisfies Equation 1. The film thicknesses of the dielectric films in the first and second edge regions are smaller than the dielectric film in the central region.

Abstract: In an acoustic wave device, an IDT electrode is located on a piezoelectric layer. A high-acoustic-velocity member is positioned on an opposite side of the piezoelectric layer from the IDT electrode. An acoustic velocity of a bulk wave propagating through the high-acoustic-velocity member is higher than an acoustic velocity of an acoustic wave propagating through the piezoelectric layer. A low-acoustic-velocity film is provided between the high-acoustic-velocity member and the piezoelectric layer. An acoustic velocity of a bulk wave propagating through the low-acoustic-velocity film is lower than the acoustic velocity of the bulk wave propagating through the piezoelectric layer. A dielectric film is located on the piezoelectric layer so as to cover the IDT electrode. In the acoustic wave device, a Young's modulus of the dielectric film is larger than a Young's modulus of the low-acoustic-velocity film.

Abstract: An acoustic wave device includes a piezoelectric substrate, and an IDT electrode on the piezoelectric substrate. The piezoelectric substrate includes a high acoustic velocity layer, and a piezoelectric layer. The IDT electrode includes a first busbar and a second busbar, and first and second electrode fingers interdigitated with each other. A first envelope and a second envelope each extend in a slanted direction with respect to an acoustic wave propagation direction, the first envelope being an imaginary line formed by connecting tips of the first electrode fingers, the second envelope being an imaginary line formed by connecting tips of the second electrode fingers. The first dielectric film is located in at least one gap of first and second gaps, the first gaps being located between the first electrode fingers and the second busbar, the second gaps being located between the second electrode fingers and the first busbar. The first dielectric film has a density greater than a density of silicon oxide.

Abstract: A first filter of a multiplexer includes serial resonators and parallel resonators that are acoustic wave resonators. A first of the serial resonators that is closer to a common terminal than the other serial resonators is connected to the common terminal without the parallel resonators interposed therebetween. Each of the elastic wave resonators includes a substrate having piezoelectricity, an IDT electrode provided on the substrate, and a dielectric layer provided on the substrate to cover the IDT electrode. A thickness of the dielectric layer of the first serial resonator is smaller than a thickness of each of the dielectric layers of the remainder of the elastic wave resonators.

Abstract: An acoustic wave device includes a piezoelectric body including first and second main surfaces facing each other, an IDT electrode provided on the first main surface of the piezoelectric body and including electrode fingers, a high acoustic velocity member on the second main surface side of the piezoelectric body, in which an acoustic velocity of a propagating bulk wave is higher than an acoustic velocity of an acoustic wave propagating through the piezoelectric body, and a first dielectric film provided on an upper surface of the electrode fingers, in which a portion where a dielectric is not present is provided between the electrode fingers of the IDT electrode.

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: A notch filter includes a substrate having piezoelectricity, the substrate including a high-acoustic-velocity member, a low-acoustic-velocity film provided on the high-acoustic-velocity member, and a piezoelectric thin film provided on the low-acoustic-velocity film; an interdigital transducer electrode provided on the piezoelectric thin film; and reflectors provided on both sides of the interdigital transducer electrode in an acoustic wave propagation direction. An IR gap is within one of two ranges: 0.1??GIR<0.5? or 0.5?<GIR?0.9?, where ? is a wavelength determined by an electrode finger pitch of the interdigital transducer electrode, and the IR gap is a distance between electrode finger centers of an electrode finger of the interdigital transducer electrode closest to the reflector out of the electrode fingers of the interdigital transducer electrode, and an electrode finger of the reflector closest to the interdigital transducer electrode, out of the electrode fingers of the reflector.

Abstract: An acoustic wave device includes a piezoelectric substrate and an IDT electrode on the piezoelectric substrate. The IDT electrode includes a first busbar and a second busbar that oppose each other, multiple first electrode fingers, multiple second electrode fingers, multiple first offset electrodes, and multiple second offset electrodes. A virtual line connecting the leading ends of the first electrode fingers is referred to as a first envelope. The first envelope is included relative to the acoustic-wave propagation direction. A virtual line connecting the leading ends of the second electrode fingers is referred to as a second envelope. The second envelope is inclined relative to the acoustic-wave propagation direction. The direction in which the first offset electrodes extend and the direction in which the second offset electrodes extend inclined relative to the direction orthogonal or substantially orthogonal to the acoustic-wave propagation direction.

Abstract: An acoustic wave device includes an IDT electrode on a piezoelectric body and the IDT electrode includes first and second busbars, and first and second electrode fingers. A first dielectric film extends from a region between tip end portions of the first electrode fingers and the piezoelectric body to a region between the second busbar and the piezoelectric body with a first gap in between. The second electrode fingers are in direct contact with the piezoelectric body at a center of an overlap width, and a permittivity of the first dielectric film is lower than a permittivity of the piezoelectric body.

Abstract: A first filter of a multiplexer includes serial resonators and parallel resonators that are acoustic wave resonators. A first of the serial resonators that is closer to a common terminal than the other serial resonators is connected to the common terminal without the parallel resonators interposed therebetween. Each of the elastic wave resonators includes a substrate having piezoelectricity, an IDT electrode provided on the substrate, and a dielectric layer provided on the substrate to cover the IDT electrode. A thickness of the dielectric layer of the first serial resonator is smaller than a thickness of each of the dielectric layers of the remainder of the elastic wave resonators.

Abstract: An acoustic wave device includes a support substrate and first and second resonant sections adjacent to each other on the support substrate. Each of the first and second resonant sections includes a piezoelectric thin film, an IDT electrode on the piezoelectric thin film, and a support layer surrounding the piezoelectric thin film in a plan view of the acoustic wave device. The support layer has a different linear expansion coefficient from the piezoelectric thin film. The piezoelectric thin film in the first resonant section and the piezoelectric thin film in the second resonant section are divided by the support layer between the resonant section and the resonant section.

Abstract: An elastic wave device includes a support substrate, a piezoelectric layer disposed on the support substrate, and an IDT electrode disposed on a piezoelectric layer 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.

Abstract: An acoustic wave device includes a piezoelectric substrate in which a reverse-velocity surface is convex and an IDT electrode on the piezoelectric substrate. When an acoustic wave propagation direction is a first direction and a direction perpendicular or substantially perpendicular to the first direction is a second direction, the portion of the IDT electrode where first and second electrode fingers overlap in the first direction is a crossing region. The crossing region includes a center region centrally located in the second direction and a first and second edge regions located on two sides of the center region. Recesses 17 and 18 are respectively provided in portions of the piezoelectric substrate located in the first and second edge regions between the portions where the first and second electrode fingers are provided.

Abstract: An acoustic wave device including series arm resonators including a first IDT electrode and parallel arm resonators including a second IDT electrode, in the first IDT electrode, a first envelope obliquely extends with respect to the acoustic wave propagation direction, and a second envelope obliquely extends with respect to the acoustic wave propagation direction, the second IDT electrode includes a central region, a first low acoustic velocity region in which an acoustic velocity is lower than an acoustic velocity in the central region, a second low acoustic velocity region in which an acoustic velocity is lower than the acoustic velocity in the central region, a first high acoustic velocity region in which an acoustic velocity is higher than the acoustic velocity in the central region, and a second high acoustic velocity region in which an acoustic velocity is higher than the acoustic velocity in the central region.

Abstract: 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.

Abstract: An acoustic wave device includes a piezoelectric substrate a reverse-velocity surface of which is convex, an interdigital transducer electrode disposed on the piezoelectric substrate, and mass addition films stacked above the interdigital transducer electrode. The interdigital transducer electrode includes a central region, first and second edge regions, first and second gap regions located outside the first and second edge regions, first and second inner busbar regions, and first and second outer busbar regions. The mass addition films are stacked in at least the first and second edge regions and the first and second inner busbar regions.