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.

An electroacoustic resonator (EAR) that allows RF filters in which transversal modes are suppressed in a wider frequency range and corresponding RF filters and methods are provided. The resonator has an electrode structure (BB,EF) on a piezoelectric material and a transversal acoustic wave guide. The wave guide has a central excitation area (CEA), trap stripes (TP) and barrier stripes (B). The difference in wave velocity (|VCEA−VB|) between the central excitation area and the barrier stripes determines the frequency range of suppressed transversal modes.

An acoustic wave device includes a piezoelectric substrate and an IDT electrode provided on the piezoelectric substrate. In the IDT electrode, a central region, first and second low acoustic velocity regions and first and second high acoustic velocity regions are disposed in this order. A duty ratio in the first low acoustic velocity region of first electrode fingers and the second low acoustic velocity region of second electrode fingers is larger than a duty ratio in the central region. When acoustic velocity of a transversal bulk wave propagating in metal that is a main component of a main electrode layer is defined as v (m/s), v≤3299 m/s, and when a wave length defined by an electrode finger pitch of the IDT electrode is defined as λ, and a film thickness of the main electrode layer normalized by the wave length λ is defined as T, then T≥0.00018e.sup.0.002V+0.014.

An acoustic wave device includes a piezoelectric substrate, an interdigital transducer electrode on the piezoelectric substrate, and two reflectors on both sides of the interdigital transducer electrode in an acoustic wave propagation direction. The reflectors include first and second busbars and first to third electrode fingers, respectively, and the first and second busbars are opposed to one another. The first busbars and the second busbars are connected by at least one third electrode finger. The reflectors each include a center area located centrally in a length direction and a first high-acoustic-velocity area that is located between the center area and the first busbars and has an acoustic velocity higher than the acoustic velocity of the center area, where the length direction is a direction in which the first to third electrode fingers extend.

A surface acoustic wave device includes a substrate, a first electrode and a second electrode formed on the substrate to extend along a first direction, wherein the first electrode and the second electrode are alternately disposed along the second direction, one end of the first electrode on one side of the first direction is aligned along the second direction, and one end of the second electrode on the other side of the first direction is aligned along the second direction, a temperature compensation film which covers the first electrode and the second electrode, a first additional film formed on the temperature compensation film to vertically overlap a partial region from the one end of the first electrode on the one side of the first direction, and a second additional film formed on the temperature compensation film to vertically overlap a partial region from the one end of the second electrode.

Aspects of this disclosure relate to a surface acoustic wave device. The surface acoustic wave device includes a piezoelectric layer and an interdigital transducer. The interdigital transducer electrode includes a pair of electrodes, each electrode having a bus bar and fingers extending from the bus bar. The interdigital transducer electrode has an interdigital region defined by a portion of the fingers of the electrodes that interdigitate with each other. A dielectric layer is disposed over the interdigital transducer electrode outside the interdigital region and configured to reduce a loss of the surface acoustic wave device.

Aspects of this disclosure relate to an acoustic wave resonator with hyperbolic mode suppression. The acoustic wave resonator can include a piezoelectric layer, an interdigital transducer electrode, a temperature compensation layer, and a mass loading strip. The mass loading strip can be a conductive strip. The mass loading strip can overlap edge portions of fingers of the interdigital transducer electrode. A layer of the mass loading strip can have a density that is at least as high as a density of a material of the interdigital transducer electrode. The material of the interdigital transducer can impact acoustic properties of the acoustic wave resonator.

Aspects of this disclosure relate to an acoustic wave resonator with transverse mode suppression. The acoustic wave resonator can include a piezoelectric layer, an interdigital transducer electrode, a temperature compensation layer, and a mass loading strip. The mass loading strip can be a conductive strip. The mass loading strip can overlap edge portions of fingers of the interdigital transducer electrode. A layer of the mass loading strip can have a density that is at least as high as a density of a material of the interdigital transducer electrode. The material of the interdigital transducer can impact acoustic properties of the acoustic wave resonator.

An acoustic wave device comprises a substrate including a piezoelectric material, and interdigital transducer (IDT) electrodes disposed on a surface of the substrate. The IDT electrodes have gap regions, edge regions, and center regions. A maximum width of the IDT electrodes in the gap regions is greater than the maximum width of the IDT electrodes in the edge regions, thereby achieving a velocity of an acoustic wave in the gap regions being greater than the velocity of the acoustic wave in the center regions, and the velocity of the acoustic wave in the center regions being greater than the velocity of the acoustic wave in the edge regions.

An acoustic wave device comprises a substrate including a piezoelectric material, interdigital transducer (IDT) electrodes disposed on a surface of the substrate, the IDT electrodes having gap regions, edge regions, and center regions, a first dielectric film having a lower surface disposed on the IDT electrodes and the surface of the substrate, and a material having a density greater than a density of the first dielectric film disposed above the gap regions of the IDT electrodes.