An acoustic wave device includes a supporting substrate, an acoustic reflection layer, a piezoelectric layer, and an IDT electrode. At least one of a high acoustic impedance layer and a low acoustic impedance layer is a conductive layer in the acoustic reflection layer. When a wavelength of an acoustic wave determined by an electrode finger pitch of the IDT electrode is λ and a region between an envelope of tips of first electrode fingers and an envelope of tips of second electrode fingers is an intersecting region, the conductive layer overlaps at least the intersecting region in plan view in a thickness direction of the supporting substrate, and a distance from the tips of the first electrode fingers to an end of the conductive layer in a direction in which the first electrode fingers extend is more than 0 and not more than about 12λ.

In an acoustic wave device, an IDT electrode is located on a piezoelectric layer. A high-acoustic-velocity member is positioned on an opposite side of the piezoelectric layer from the IDT electrode. An acoustic velocity of a bulk wave propagating through the high-acoustic-velocity member is higher than an acoustic velocity of an acoustic wave propagating through the piezoelectric layer. A low-acoustic-velocity film is provided between the high-acoustic-velocity member and the piezoelectric layer. An acoustic velocity of a bulk wave propagating through the low-acoustic-velocity film is lower than the acoustic velocity of the bulk wave propagating through the piezoelectric layer. A dielectric film is located on the piezoelectric layer so as to cover the IDT electrode. In the acoustic wave device, a Young's modulus of the dielectric film is larger than a Young's modulus of the low-acoustic-velocity film.

An acoustic wave device includes: a first substrate that has a first surface and a second surface, the second surface being an opposite surface of the first substrate from the first surface; an acoustic wave element that is located on the first surface; a wiring portion that electrically connects the acoustic wave element and a metal portion through a through hole, the metal portion being located on the second surface, the through hole penetrating through the first substrate; and a sealing portion that is located on the first surface so as to surround the acoustic wave element, overlaps with at least a part of the through hole in plan view, and seals the acoustic wave element in an air gap.

A longitudinally coupled resonator type surface acoustic wave filter includes a high-acoustic-velocity member, a low-acoustic-velocity film provided on the high-acoustic-velocity member, a piezoelectric film provided on the low-acoustic-velocity film, a plurality of interdigital transducers provided on the piezoelectric film and along a propagation direction of a surface acoustic wave and each including a plurality of electrode fingers, and reflectors arranged such that the interdigital transducers are interposed therebetween from both sides in the propagation direction of the surface acoustic wave. An electrode finger pitch is uniform or substantially uniform in each of the interdigital transducers. When a wavelength determined by the electrode finger pitch in the reflector is defined as λ, an inter-electrode finger center distance that is an interval between each of the interdigital transducers and the interdigital transducer adjacent thereto is not shorter than about 0.25λ and not longer than about 0.37λ.

A surface acoustic wave device includes a piezoelectric substrate, an IDT electrode, a support layer, a cover layer, and a pillar-shaped electrode. The IDT electrode is provided on a main surface of the piezoelectric substrate. The support layer is disposed around a region where the IDT electrode is provided and has a larger height from the main surfaces than a height of the IDT electrode therefrom. The cover layer is disposed on the support layer and covers the IDT electrode. The pillar-shaped electrode is located on one of the main surfaces where the pillar-shaped electrode is in contact with the support layer. The pillar-shaped electrode is electrically connected to the IDT electrode. The pillar-shaped electrode includes a top surface and a side surface. Each of the top surface and the side surface includes a portion exposed to outside.

A wafer arrangement comprises a carrier wafer (CW) having a top surface divided into a regular pattern (RP) of first CA (SA1, ARS) and second surface areas (SA2, PES), wherein each first surface area is assigned to an adjacently applied respective separate second surface area to form together a combined filter area. Spots of thin film piezoelectric material are bonded to the first surface areas. Circuits of LC elements (PES) are formed integrally on the second surface areas from a multi-level metallization (ML1, ML2). The LC elements of each metallization level being embedded in a dielectric.

A surface acoustic wave resonator includes first and second surface acoustic wave resonator connected in series, and a third surface acoustic wave resonator connected in series with the second surface acoustic wave resonator. Each of the first to third surface acoustic wave resonators includes a pair of comb-shaped electrodes in which electrode fingers of one of the comb-shaped electrodes and electrode fingers of the other one of the comb-shaped electrodes are alternately arranged. The second surface acoustic wave resonator has a lower ratio of a width of the electrode fingers to a pitch between the electrode fingers than the first and third surface acoustic wave resonators.

A passive wireless sensor includes a substrate having at least one Microelectromechanical system (MEMS) piezoelectric resonator thereon. The MEMS piezoelectric resonator includes a piezoelectric layer between a top metal or semiconductor layer (top electrode layer) and a bottom metal or semiconductor layer (bottom electrode layer). The top electrode layer is a patterned top electrode layer including at least a first electrode for sensing an electrical signal and a second electrode for providing a ground reference. An antenna is connected to the first and/or second electrode for wirelessly transmitting the electrical signal and for receiving a wireless interrogation signal.

A surface elastic wave resonator comprises a piezoelectric material to propagate the surface elastic waves and a transducer inserted between a pair of reflectors comprising combs of interdigitated electrodes and having a number Nc of electrodes connected to a hot spot and an acoustic aperture W wherein the relative permittivity of the piezoelectric material is greater than about 15, a product of Nc.Math.W/fa for the transducer being greater than 100 m.Math.MHz.sup.1, where fa is the antiresonance frequency of the resonator. A circuit comprises a load impedance and a resonator according to the invention and having an electrical response manifesting as a peak in the coefficient of reflection S.sub.11 at a frequency of a minimum value of the parameter S.sub.11 that is lower than 10 dB, the antiresonance peak of the resonator being matched to the impedance of the load.

An electronic filter comprises a high pass section (110) and a low pass section (120). The high pass section includes at least one filter stage of a series-connected acoustic resonator (111) and a parallel connected inductor (114). The low pass section comprises at least one filter stage including a series-connected inductor (121) and a parallel connected acoustic resonator (123). The filter is useful for a communication device covering the n79 5G band.