A surface acoustic wave device: includes at least one transducer; two acoustic reflectors disposed on either side of the at least one transducer so as to form a cavity, each acoustic reflector comprising an array of electrodes in the form of lines parallel with each other, each array comprising a subset of electrodes connected to a reference potential denoted mass defining a first connection type, and a subset of electrodes that are not connected to any potential, i.e. that have a floating connection defining a second connection type; at least one switching circuit configured to modify the distribution of the connections of at least one part of the electrodes of each array between the different connection types.

In order to pass a signal having a wide pass bandwidth with respect to a center frequency of a pass band, a surface acoustic wave device includes a first surface acoustic wave element provided with a first pass band; and a second surface acoustic wave element having a second pass band in a high frequency band compared with the first pass band of the first surface acoustic wave element, in which the first surface acoustic wave element and the second surface acoustic wave element have a common input terminal and a common output terminal, and a frequency of a high frequency side of the first pass band of the first surface acoustic wave element is partially overlapped with a frequency of a low frequency side of the second pass band of the second surface acoustic wave element.

An elastic wave device includes a supporting substrate, an acoustic multilayer film on the supporting substrate, a piezoelectric substrate on the acoustic multilayer film, and an IDT electrode on the piezoelectric substrate. The acoustic multilayer film includes at least four acoustic impedance layers. The at least four acoustic impedance layers include at least one low acoustic impedance layer and at least one high acoustic impedance layer having an acoustic impedance higher than the low acoustic impedance layer. The elastic wave device further includes a bonding layer provided at any position in a range of from inside the acoustic impedance layer, which is the fourth acoustic impedance layer from the piezoelectric substrate side towards the supporting substrate side, to an interface between the acoustic multilayer film and the supporting substrate.

Aspects of the disclosure relate to wireless communication, and high-frequency filters with resonators. One example is a frequency band filter circuit having a split resonator. The split resonator comprises a resonator including a first section of a shared input busbar, a first section of a shared output busbar, and an electrode structure between the first section of the shared input busbar and the first section of the shared output busbar, the electrode structure configured for a resonance. The split resonator also comprises a detuned resonator. The detuned resonator includes a second section of the shared input busbar, a second section of the shared output busbar, and a detuned electrode structure between the second section of the shared input busbar and the second section of the shared output busbar, the detuned electrode structure configured for a detuned resonance different from the resonance.

An elastic wave device includes a support substrate, a polycrystalline nanodiamond layer provided directly or indirectly on the support substrate, at least one inorganic material layer provided on the polycrystalline nanodiamond layer, a piezoelectric body provided directly or indirectly on the at least one inorganic material layer, and an IDT electrode provided directly or indirectly on the piezoelectric body. The piezoelectric body propagates an elastic wave at a higher velocity than the polycrystalline nanodiamond layer propagates a bulk wave, and at a lower velocity than the at least one inorganic material layer propagates a bulk wave. The polycrystalline nanodiamond layer has a percentage of sp3 bonds of about 50% or more.

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.

An acoustic wave device includes a piezoelectric substrate, an interdigital transducer electrode on the piezoelectric substrate, and reflectors. The interdigital transducer electrode includes first and second busbars including first and second cavities in a first direction, and first and second edge regions and first and second gap regions. The first and second edge regions include low acoustic velocity regions. Regions in which the first and second cavities are provided include high acoustic velocity regions. The reflector includes first and second reflector busbars and first reflection electrode fingers each including a second end portion that faces the second reflector busbar. The first reflection electrode fingers overlap the entire or substantially the entire second gap region when viewed in the first direction.

An acoustic wave filter device includes a longitudinally coupled resonator acoustic wave filter on a series arm that connects an input terminal and an output terminal, first and second parallel arm resonators on first and second parallel arms that connect the series arm and a ground potential, an input-side ground port of the longitudinally coupled resonator acoustic wave filter and a ground port of at least one of the first and second parallel arm resonators are connected in common, an output-side ground port of the longitudinally coupled resonator acoustic wave filter and a ground port of at least another of the first and second parallel arm resonators are connected in common, and an electrostatic capacitance of the first parallel arm resonator is different from an electrostatic capacitance of the second parallel arm resonator.

An elastic wave device includes a piezoelectric substrate made of LiNbO.sub.3, an IDT electrode on the piezoelectric substrate, and a dielectric film on the piezoelectric substrate and covering the IDT electrode. The IDT electrode includes a first electrode layer on or above the piezoelectric substrate and including W or an alloy including W, and a second electrode layer on or above the first electrode layer. A thickness of the first electrode layer is not smaller than 0.062λ, λ being a wavelength determined by a pitch of electrode fingers of the IDT electrode. The piezoelectric substrate has Euler angles of (0°± about 5°, θ, 0°± about 10°), ↓ being not smaller than 8° and not larger than 32°.

An acoustic wave element which can be reduced in size and produced relatively easily, practically used without using harmful substances, and can suppress a surface acoustic wave propagation loss, which has an excellent temperature coefficient of frequency and a velocity dispersion characteristic, and with which an increase in the reflection coefficient of interdigital transducers can be suppressed, and a method for manufacturing the acoustic wave element are provided. The acoustic wave element includes a pair of electrodes provided on both surfaces of a piezoelectric substrate, and a dielectric film provided on a first surface of the piezoelectric substrate so as to cover the electrode. The acoustic wave element alternatively includes interdigital transducers provided on a first surface of the piezoelectric substrate, and a dielectric film provided on the interdigital transducers, a gap between the interdigital transducers, and/or a second surface of the piezoelectric substrate.