Abstract: An acoustic wave filter provided herein comprises a plurality of series resonators, and a plurality of shunt resonators disposed between the series resonators and a ground, at least one shunt resonator including a substrate, a pair of IDT electrodes disposed on the substrate, each of the IDT electrodes including a bus bar and a plurality of fingers extending from the bus bar, the plurality of fingers of the pair of IDT electrodes including a first group of fingers located at a center region of the pair of IDT electrodes and a second group of fingers located at edge regions on both sides of the center region, the first group of fingers having an average pitch distance shorter than an average pitch distance of the second group of fingers to improve a response at a rejection band of the acoustic wave filter.

Abstract: A multi-band filter configured to allow signals to pass at multiple frequency bands includes a piezoelectric substrate and a plurality of groups of electrodes disposed on the piezoelectric substrate. Each group forms a respective filter to allow signals to pass at a corresponding frequency band. A first group forms a first filter having a first frequency band and a second group forms a second filter having a second frequency band. The first frequency band is lower than the second frequency band. The filter includes a dielectric film formed to cover at least a part of the piezoelectric substrate and the plurality of groups of electrodes. The filter also includes a passivation film disposed on the dielectric film. The passivation film has a smaller thickness for the first group than for the second group, so as to suppress a spurious response generated in the piezoelectric substrate.

Abstract: An acoustic wave device includes: a Y-cut X-propagation lithium tantalate substrate having a cut angle of 5° or greater and 18° or less; and a grating electrode that is formed of one or more metal films stacked on the lithium tantalate substrate, a number of the one or more metal films being n (n is a natural number), excites an acoustic wave, and meets a condition: 0.16 ? ? ? ? i = 1 n ? ? ( hi × ? ? ? i ? ? ? 0 ) ? 0.24 ? ? where ?i represents a density of each metal film of the one or more metal films, hi represents a film thickness of the each metal film, ?0 represents a density of Mo, and ? represents a pitch.

Abstract: An acoustic wave device includes: a piezoelectric substrate; and a pair of comb-shaped electrodes located on the piezoelectric substrate, each of the comb-shaped electrodes including a plurality of electrode fingers, side surfaces facing each other of the electrode fingers having a plurality of protrusion portions and a plurality of recessed portions arranged in an extension direction of the electrode fingers, ends of the protrusion portions and the recessed portions narrowing.

Abstract: An acoustic wave device includes: a piezoelectric substrate; and a pair of comb-shaped electrodes located on the piezoelectric substrate, each of the comb-shaped electrodes being formed mainly of a monocrystalline metal film, each of the comb-shaped electrodes including electrode fingers.

Abstract: An acoustic wave resonator includes: a piezoelectric substrate that is a lithium tantalate substrate or a lithium niobate substrate and has a thickness of 20 ?m or less; a support substrate that has an upper surface bonded with a lower surface of the piezoelectric substrate And is a glass substrate mainly composed of silicon oxide; a plurality of electrode fingers that are located on an upper surface of the piezoelectric substrate, excite an acoustic wave, and include a metal film mainly composed of at least one of Cr, Mo, and W.

Abstract: An acoustic wave resonator includes: a piezoelectric substrate; and an IDT that is located on the piezoelectric substrate and includes comb-shaped electrodes facing each other, each of the comb-shaped electrodes having grating electrode and a bus bar connected to the grating electrodes, a duty ratio of grating electrodes of the comb-shaped electrodes in a center region of an overlap region differing from a duty ratio of grating electrodes of the comb-shaped electrodes in an edge region of the overlap region in an arrangement direction of the grating electrodes, the grating electrodes of each of the comb-shaped electrodes overlapping with the grating electrodes of the other in the overlap region, a grating electrode of a first one of the comb-shaped electrodes in the center region having a different width from a grating electrode of a second one of the comb-shaped electrodes in the center region.

Abstract: An acoustic wave device includes: a piezoelectric substrate; and a pair of comb-shaped electrodes that is located on the piezoelectric substrate, includes a metal film, and excites a surface acoustic wave, the metal film being mainly composed of a metal having a melting point equal to or higher than a melting point of Pt, the metal film having a first region in which a crystal grain has a columnar shape and a second region that is located on and/or under the first region in a stacking direction and has less crystallinity than the first region or has an amorphous structure.

Abstract: An acoustic wave device includes: a piezoelectric substrate; and a pair of comb-shaped electrodes located on the piezoelectric substrate, each of the comb-shaped electrodes including a plurality of electrode fingers, side surfaces facing each other of the electrode fingers having a plurality of protrusion portions and a plurality of recessed portions arranged in an extension direction of the electrode fingers, ends of the protrusion portions and the recessed portions narrowing.

Abstract: An acoustic wave device includes: a piezoelectric substrate; and a pair of comb-shaped electrodes located on the piezoelectric substrate, each of the comb-shaped electrodes being formed mainly of a monocrystalline metal film, each of the comb-shaped electrodes including electrode fingers.

Abstract: A multiplexer includes: a first filter including a series resonator connected in series and a parallel resonator connected in parallel between a common terminal and a first terminal, each of the series resonator and the parallel resonator including an IDT located on a piezoelectric substrate, first and second regions being alternately located in an extension direction of electrode fingers, which excite an acoustic wave, within an overlap region of the IDT in which the electrode fingers overlap, a width of at least one of the electrode fingers in the second region being greater than that in the first region, one or some resonators of the parallel resonator and the series resonator having a larger number of the second regions than a remaining resonator; and a second filter connected between the common terminal and a second terminal and having a passband higher than a passband of the first filter.

Abstract: An acoustic wave resonator includes: a piezoelectric substrate; and an IDT that is located on the piezoelectric substrate and includes first regions and second regions alternately arranged in an extension direction of electrode fingers, which excite an acoustic wave, in an overlap region in which the electrode fingers overlap, at least one electrode finger of the electrode fingers in the second regions having a different width from the at least one electrode finger in the first regions, a width of an outer second region of the second regions in the extension direction differs from a width of an inner second region of the second regions.

Abstract: An acoustic wave device includes: a Y-cut X-propagation lithium tantalate substrate having a cut angle of 5° or greater and 18° or less; and a grating electrode that is formed of one or more metal films stacked on the lithium tantalate substrate, a number of the one or more metal films being n (n is a natural number), excites an acoustic wave, and meets a condition: 0.16 ? ? ? ? i = 1 n ? ? ( hi × ? ? ? i ? ? ? 0 ) ? 0.24 ? ? where ?i represents a density of each metal film of the one or more metal films, hi represents a film thickness of the each metal film, ?0 represents a density of Mo, and ? represents a pitch.

Abstract: An acoustic wave resonator includes: a piezoelectric substrate; and an IDT located on the piezoelectric substrate and including a pair of comb-shaped electrodes facing each other, each of the pair of comb-shaped electrodes including a grating electrode exciting an acoustic wave and a bus bar to which the grating electrode is connected, wherein an anisotropy coefficient in a cross region where the grating electrodes of the pair of comb-shaped electrodes cross each other is positive; an anisotropy coefficient in a gap region located between a tip of the grating electrode of one of the pair of comb-shaped electrodes and the bus bar of the other is less than the anisotropy coefficient in the cross region, and an acoustic velocity of an acoustic wave propagating through the gap region is equal to or less than an acoustic velocity of an acoustic wave propagating through the cross region at an antiresonant frequency.

Abstract: An acoustic wave resonator includes: a piezoelectric substrate; and an IDT that is located on the piezoelectric substrate and includes comb-shaped electrodes facing each other, each of the comb-shaped electrodes having grating electrode and a bus bar connected to the grating electrodes, a duty ratio of grating electrodes of the comb-shaped electrodes in a center region of an overlap region differing from a duty ratio of grating electrodes of the comb-shaped electrodes in an edge region of the overlap region in an arrangement direction of the grating electrodes, the grating electrodes of each of the comb-shaped electrodes overlapping with the grating electrodes of the other in the overlap region, a grating electrode of a first one of the comb-shaped electrodes in the center region having a different width from a grating electrode of a second one of the comb-shaped electrodes in the center region.

Abstract: An acoustic wave device includes: a Y-cut X-propagation lithium tantalate substrate having a cut angle of 20° or more and 48° or less; and a grating electrode that is composed of one or more metal films laminated on the substrate, and excites an acoustic wave, wherein when a density of each metal film in the one or more metal films is represented by ?i, a Poisson's ratio of each metal film is represented by Pi, a film thickness of each metal film is represented by hi, a density of Cu is represented by ?0, a Poisson's ratio of Cu is represented by P0 and a pitch is represented by ?, a total value of “(hi/?)×(?i/?0)×(Pi/P0)” for each metal film with respect to the one or more metal films is more than 0.08.

Abstract: An acoustic wave device includes: a piezoelectric substrate; and a pair of comb-shaped electrodes that is located on the piezoelectric substrate, includes a metal film, and excites a surface acoustic wave, the metal film being mainly composed of a metal having a melting point equal to or higher than a melting point of Pt, the metal film having a first region in which a crystal grain has a columnar shape and a second region that is located on and/or under the first region in a stacking direction and has less crystallinity than the first region or has an amorphous structure.

Abstract: An acoustic wave resonator includes: a piezoelectric substrate; and a pair of grating electrodes that is formed on the piezoelectric substrate, one of the pair of grating electrodes including a plurality of first electrode fingers having electric potentials equal to each other, another of the pair of grating electrodes including a plurality of second electrode fingers having electric potentials that differ from the electric potentials of the plurality of first electrode fingers and are equal to each other, two second electrode fingers of the plurality of second electrode fingers being located between at least a pair of adjacent first electrode fingers of the plurality of first electrode fingers, Pg differing from ?/4 where ? represents a wavelength of an acoustic wave excited by the plurality of first electrode fingers and the plurality of second electrode fingers and Pg represents a distance between centers of the two second electrode fingers.

Abstract: An acoustic wave resonator includes: a piezoelectric substrate that is a lithium tantalate substrate or a lithium niobate substrate and has a thickness of 20 ?m or less; a support substrate that has an upper surface bonded with a lower surface of the piezoelectric substrate And is a glass substrate mainly composed of silicon oxide; a plurality of electrode fingers that are located on an upper surface of the piezoelectric substrate, excite an acoustic wave, and include a metal film mainly composed of at least one of Cr, Mo, and W.

Abstract: An acoustic wave element includes: a piezoelectric substrate; an IDT (Interdigital Transducer) formed on the piezoelectric substrate; and an end face of the piezoelectric substrate that is formed on at least one end of the IDT in a propagation direction of an acoustic wave; wherein when a wavelength of the acoustic wave which the IDT excites is expressed by “?” and a metallization ratio of the IDT is expressed by “D”, a distance between an inner end of an electrode finger of the IDT nearest to the end face and the end face is equal to or more than 7?/16+D×?/4 and equal to or less than 3?/4+D×?/4.