An acoustic wave device includes a high-acoustic-velocity film, a low-acoustic-velocity film, a piezoelectric layer including lithium tantalate, and an IDT electrode on the piezoelectric layer. The IDT electrode includes first and second busbars and first and second electrode fingers. An intersecting region is a portion where the first and second electrode fingers overlap in an acoustic wave propagation direction. The intersecting region includes a central region and first and second edge regions. The IDT electrode includes first and second gap regions outside the first and second edge regions. The first and second electrode fingers are wider in the first and second edge regions than in the central region. A duty ratio in the first and second edge regions is from about 0.62 to about 0.73.

An acoustic wave filter includes acoustic wave resonators including a piezoelectric substrate and an IDT electrode including first and second electrode fingers. An intersecting region of the first and second electrode fingers includes a central region and first and second edge regions on outer side portions of the central region. An acoustic velocity in the first and second edge regions is lower than that in the central region, and the acoustic wave resonators include a first acoustic wave resonator with a width in the first and second edge regions larger than a width in the central region, and a second acoustic wave resonator including at least one of an acoustic velocity reducing film and an acoustic velocity increasing film in the central region, such that an acoustic velocity in the first and second edge regions is lower than acoustic velocity in the center region.

Certain aspects of the present disclosure provide a surface acoustic wave (SAW) resonator with piston mode design and electrostatic discharge (ESD) protections. An example electroacoustic device generally includes a piezoelectric material and a first electrode structure disposed above the piezoelectric material. The first electrode structure comprises first electrode fingers arranged within an active region having a first region and a second region. At least one of the first electrode fingers has at least one of a different width or a different height in the first region than in the second region, and the first electrode fingers comprise a first electrode finger that has a width or height in the second region that is less than a corresponding width or height of the at least one of the first electrode fingers in the second region.

An acoustic wave device includes a piezoelectric layer and an interdigital transducer electrode disposed over the piezoelectric layer. The interdigital transducer electrode is thicker in a center region of the interdigital transducer electrode than in a gap region of the interdigital transducer electrode to thereby reduce a mass loading of the interdigital transducer electrode in the gap region. The interdigital transducer electrode has a layer of more dense material disposed of a layer of less dense material.

An acoustic wave device includes a piezoelectric layer and an interdigital transducer electrode disposed over the piezoelectric layer. The interdigital transducer electrode is thicker in a center region of the interdigital transducer electrode than in a gap region of the interdigital transducer electrode to thereby reduce a mass loading of the interdigital transducer electrode in the gap region. The interdigital transducer electrode has a layer of less dense material disposed of a layer of more dense material.

An acoustic wave filter includes a piezoelectric layer. A first acoustic wave device includes a portion of the piezoelectric layer and a first multi-layer interdigital transducer electrode disposed over the first portion of the piezoelectric layer. Additional acoustic wave devices are coupled to the first acoustic wave device, the additional acoustic wave devices including a second portion of the piezoelectric layer and a plurality of multi-layer interdigital transducer electrodes disposed over the second portion of the piezoelectric layer. At least one of the plurality of multi-layer interdigital transducer electrodes includes a layer that is thinner than a corresponding layer of the same material of the first multi-layer interdigital transducer electrode of the first acoustic wave device.

An acoustic wave device comprises a substrate including a piezoelectric material, interdigital transducer (IDT) electrodes disposed on an upper surface of the substrate. The IDT electrodes having gap regions, edge regions, and center regions. A duty factor of the IDT electrodes in the edge regions is greater than the duty factor of the IDT electrodes in the center regions. A first dielectric film is disposed above the IDT electrodes and an upper surface of the substrate. The first dielectric film has a greater thickness in portions of the center regions than in portions proximate the gap regions.

An acoustic wave device includes first and second acoustic wave resonator units. In a first IDT electrode of the first acoustic wave resonator unit, an intersecting width region includes a central region and first and second low acoustic velocity regions at outer side portions of the central region. The first and second high acoustic velocity regions include openings along an acoustic wave propagation direction. In the second acoustic wave resonator unit, a second IDT electrode includes a central region and first and second low acoustic velocity regions at outer side portions in an intersecting width direction of the central region. At an outer side portion of the first low acoustic velocity region, openings are at a third busbar. At an outer side portion of the second low acoustic velocity region, openings are not provided for a fourth busbar.

An acoustic wave device includes a dielectric film covering an IDT electrode. The IDT electrode includes first and second edge regions and first and second high acoustic velocity regions. The first and second edge regions are low acoustic velocity regions. The first and second high acoustic velocity regions are on outer sides of an intersecting width region where first and second electrode fingers are adjacent to each other in an acoustic wave propagation direction. A thickness of the dielectric film on the first and second edge regions is greater than that of the dielectric film on the first and second high acoustic velocity regions.

An elastic wave device includes a substrate, a multilayer film located on the substrate, a piezoelectric layer located on the multilayer film, and an IDT electrode located on the piezoelectric layer. The IDT electrode includes electrode fingers each having a large width from a portion connected to a busbar to a position overlapping tip ends of the other electrode fingers when viewed in an arrangement direction of the electrode fingers.