Abstract: An acoustic wave device is provided between a first terminal that is an antenna terminal and a second terminal that is different from the first terminal, and includes a plurality of acoustic wave resonators. The plurality of acoustic wave resonators include a plurality of series arm resonators and a plurality of parallel arm resonators. When the acoustic wave resonator electrically closest to the first terminal among the plurality of acoustic wave resonators is an antenna end resonator, the antenna end resonator is a SAW resonator or a BAW resonator. At least one acoustic wave resonator other than the antenna end resonator among the plurality of acoustic wave resonators is a first acoustic wave resonator.

Abstract: An acoustic wave device includes a high acoustic velocity structure, a low acoustic velocity layer on the high acoustic velocity structure, a piezoelectric layer directly or indirectly on the low acoustic velocity layer, and an electrode on the piezoelectric layer. The low acoustic velocity layer is made of a dielectric material having a lower Young's modulus than silicon oxide, or includes the dielectric material as a main component.

Abstract: In an acoustic wave device, a piezoelectric layer is provided directly or indirectly on a support substrate, an IDT electrode is provided on the piezoelectric layer, an overlap region includes a middle region and first and second edge regions, and first and second conductive layers are provided on a second main surface of the piezoelectric layer to overlap at least some portions of the first and second edge regions in plan view and at least some portions of first and second busbars in plan view.

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: An acoustic wave device includes a support substrate, a quartz-crystal layer provided directly or indirectly on the support substrate, a piezoelectric layer on the quartz-crystal layer, and an IDT electrode on the piezoelectric layer. When ? represents a wavelength defined by an electrode finger pitch of the IDT electrode, a thickness of the quartz-crystal layer is about 0.2? or more and about 0.4? or less, and the piezoelectric layer has a thickness smaller than the thickness of the quartz-crystal layer.

Abstract: An acoustic wave device includes a piezoelectric substrate and an IDT electrode including electrode fingers. A portion of the IDT electrode in which the electrode fingers overlap with each other in a propagation direction of an acoustic wave is an intersecting region. The intersecting region includes a central region on a center side in an extending direction of the electrode fingers, and a first region and a second region located on respective sides of the central region in the extending direction of the electrode fingers. In the central region, a dielectric film is provided between the electrode fingers, and the dielectric film does not overlap with at least a portion of the electrode fingers when seen in plan view.

Abstract: An acoustic wave device includes a support substrate, a piezoelectric film on the support substrate, and an IDT electrode on the piezoelectric film. A film thickness of the piezoelectric film is equal to or less than about 1? when ? is a wavelength of an acoustic wave determined by an electrode finger period of the IDT electrode. The piezoelectric film includes first and second regions in a thickness direction of the piezoelectric film. A first density that is a density in the first region and a second density that is a density in the second region are different from each other.

Abstract: An acoustic wave device including an IDT electrode on a piezoelectric film, in which a Z-axis direction of a crystal is different from a direction of a normal to a major surface. An overlap region of the IDT electrode includes a central region and first and second edge regions. First and second dielectric films are stacked between the piezoelectric film and first and second electrode fingers in the first and second edge regions. When an angle between a first side surface of the first dielectric film and a major surface of the piezoelectric film is ?1 and an angle between a second side surface of the second dielectric film and the major surface of the piezoelectric film is ?2, ?1??2 between at least one electrode finger of the first and second electrode fingers and the piezoelectric film.

Abstract: An acoustic wave device includes a silicon substrate, a first high-acoustic-velocity film on the silicon substrate, a first low-acoustic-velocity film on the first high-acoustic-velocity film, a second low-acoustic-velocity film on the first low-acoustic-velocity film, a second high-acoustic-velocity film on the second low-acoustic-velocity film, a piezoelectric film on the second high-acoustic-velocity film, and an IDT electrode on the piezoelectric film. Acoustic velocities of bulk waves propagating through the first and second high-acoustic-velocity films are higher than an acoustic velocity of an acoustic wave propagating through the piezoelectric film. Acoustic velocities of bulk waves propagating through the first and second low-acoustic-velocity films are lower than an acoustic velocity of a bulk wave propagating through the piezoelectric film. Materials of the first and second low-acoustic-velocity films are different from each other.

Abstract: In an acoustic wave device, an interdigital transducer electrode is disposed on a piezoelectric substrate with a reverse velocity surface having an elliptic shape, and a dielectric film is disposed to cover the interdigital transducer electrode. Assuming an electrode density (%) of the interdigital transducer electrode to be y (%) and a wavelength-normalized film thickness 100h/? (%) of the interdigital transducer electrode to be x (%), the wavelength-normalized film thickness x of the interdigital transducer electrode takes a value not less than x satisfying y=0.3452x2?6.0964x+36.262 depending on the electrode density of the interdigital transducer electrode.

Abstract: An acoustic wave device includes a piezoelectric layer and first and second electrodes. The first and second electrodes face each other in a direction intersecting with a thickness direction of the piezoelectric layer. The acoustic wave device uses a bulk wave of a thickness-shear primary mode. A material of the piezoelectric layer is lithium niobate or lithium tantalate. The piezoelectric layer is on a first main surface of the silicon substrate. The acoustic wave device further includes a trap region on a side of a second main surface of the piezoelectric layer.

Abstract: An acoustic wave device includes a piezoelectric substrate, an interdigital transducer (IDT) electrode provided on the piezoelectric substrate, and a pair of reflectors provided on both sides of the IDT electrode in a first direction on the piezoelectric substrate, the first direction being a propagation direction of an acoustic wave. The pair of reflectors include a plurality of electrode fingers and a plurality of electrode fingers, respectively, which extend in a second direction, the second direction being perpendicular to the first direction. The electrode finger widths of second end portions are greater than the electrode finger widths of first end portions. The electrode finger width at any given position in the electrode fingers is equal to or greater than the electrode finger width at a position closer than the given position to the first end portions.

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.

Abstract: An acoustic wave device includes a piezoelectric substrate and IDT electrodes each including a first pitch portion with a relatively wide electrode finger pitch and a second pitch portion with a relatively narrow electrode finger pitch. A central region is located on a central side in a direction in which electrode fingers extend, and first and second edge regions are located on both sides of the central region. Mass addition films are in the first and second edge regions and include first mass addition films in the first pitch portion and second mass addition films in the second pitch portion. A length of the first mass addition film along an acoustic wave propagation direction is greater than a length of the second mass addition film.

Abstract: An elastic wave device includes a piezoelectric substrate made of LiNbO3, interdigital transducer electrodes on the piezoelectric substrate, and a first dielectric film provided on the piezoelectric substrate and the first dielectric film to cover the IDT electrodes and made of a silicon oxide. The IDT electrodes include a first metal film made of one metal selected from Pt, Cu, Mo, Au, W, and Ta. The Euler angles (?, ?, ?) of the piezoelectric substrate are (0±5°, ?90°????70°, 0°±5°). The metal for the first metal film and the thickness hm/? (%) match any of the combinations as follows: Metal for the first metal film Thickness hm/? (%) of the first metal film Pt 6.5 ? hm/? ? 25 Cu ?13 ? hm/? ? 25 Mo 15.5 ? hm/? ? 25? Au 6.5 ? hm/? ? 25 W 7.5 ? hm/? ? 25 Ta ??7 ? hm/? ? 25.

Abstract: An acoustic wave device includes a multilayer substrate including a reverse-velocity surface, a piezoelectric film, a low acoustic velocity material layer, a high acoustic velocity material layer, and an IDT electrode disposed on the piezoelectric film. In the IDT electrode, gap lengths of a first gap between a tip of each of first electrode fingers and a second busbar and a second gap between a tip of each of second electrode fingers and a first busbar are about 0.23? or shorter, the gap lengths extending in an extension direction of the first and second electrode fingers.

Abstract: An acoustic wave device includes a piezoelectric substrate and an IDT electrode on the piezoelectric substrate and including electrode fingers. A portion where adjacent electrode fingers of the IDT electrode overlap each other in an acoustic wave propagation direction is an intersecting region. The intersecting region includes a central region located in a central portion in a direction in which the electrode fingers extend and first and second edge regions on both sides of the central region in the direction in which the electrode fingers extend. The acoustic wave device further includes dielectric films between the piezoelectric substrate and the electrode fingers in the first and second edge regions. The dielectric films include at least one of hafnium oxide, niobium oxide, tungsten oxide, or cerium oxide.

Abstract: An acoustic wave device includes an IDT electrode and reflector electrodes on or above a piezoelectric substrate. A region in which first and second electrode fingers of the IDT electrode overlap each other in an acoustic wave propagation direction defines an intersection region. The intersection region includes a center region and first and second edge regions on both sides of the center region. Dielectric films extend from the first and second edge regions to outer side regions in the acoustic wave propagation direction of the reflector electrodes via the reflector electrodes.

Abstract: An acoustic wave device includes an intermediate layer and a piezoelectric film that are laminated in that order on the support substrate. An interdigital transducer (IDT) electrode is provided on the piezoelectric film. Cavities are provided at least one of a location between the support substrate and the intermediate layer and a location in the intermediate layer.

Abstract: An acoustic wave device includes an IDT electrode on a piezoelectric substrate and reflector electrodes on both sides of the IDT electrode in an acoustic wave propagation direction and each including electrode fingers with gaps therebetween, and first dielectric films between the reflector electrodes and the piezoelectric substrate in regions where the electrode fingers and the gaps of the reflector electrodes are provided.