An adaptive RF acoustic resonator contains tunable and switchable hybrid surface-bulk acoustic waves (SAW-BAW). The surface and bulk acoustic waves couple for the spectral sensing and configurable filtering. The acoustic resonator includes a piezoelectric or ferroelectric layer, such as a SLAIN layer, which is patterned into interdigital transducers, and an intermediate layer of AlGaN—GaN, which is built on a SiC substrate. The device is protected under a plastic packaging cap. An external tuning voltage applies on the acoustic resonator to generate the tunable frequency and bandwidth of the bulk and surface acoustic waves. An RF switch generates an electric field to suppress a residual polarization during acoustic resonator switching. The bulk acoustic wave excited in the piezoelectric or ferroelectric layer couples with the surface acoustic wave propagating in the intermediate layer. The Sc concentration in the ferroelectric layer exceeds 28%. The transducers are capped with Bragg reflectors made of multiple Al and W layers.

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.

A Lamb wave resonator includes a piezoelectric material layer, a first finger electrode, a second finger electrode, at least two floating electrodes, and at least two gaps. The first finger electrode is disposed on one side of the piezoelectric material layer and includes a first main portion and first fingers. The second finger electrode is disposed on the side of the piezoelectric material layer and includes a second main portion and second fingers. The first fingers are parallel to and alternately arranged with the second fingers. The floating electrodes are disposed between each first finger and each second finger, and the gaps are disposed at two ends of each floating electrode, respectively.

Aspects of this disclosure relate to an acoustic wave resonator having at least two resonant frequencies. An acoustic wave filter can include series acoustic wave resonators and shunt acoustic wave resonators together arranged to filter a radio frequency signal. A first shunt resonator of the shunt acoustic wave resonators can include an interdigital transducer electrode and have at least a first resonant frequency and a second resonant frequency. Related acoustic wave resonators, multiplexers, wireless devices, and methods are disclosed.

A resonator includes an interdigital transducer provided with a main electrode area formed to a shape of a comb on a piezoelectric substrate by a reference pitch in such a manner as to have a unit length along a longitudinal direction thereof and one pair of first electrode areas constituted of one side first electrode area formed to a shape of a comb on the piezoelectric substrate by a first increment pitch obtained by increasing the reference pitch by a first value in such a manner as to have the unit length along the longitudinal direction and the other side first electrode area formed to a shape of a comb on the piezoelectric substrate by a first decrement pitch obtained by decreasing the reference pitch by almost the same value as the first value.

An acoustic wave device that includes a spinel layer, a piezoelectric layer and an interdigital transducer electrode on the piezoelectric layer is disclosed. The piezoelectric layer is disposed between the interdigital transducer electrode and the spinel layer. The acoustic wave device is configured to generate an acoustic wave having a wavelength of λ. The piezoelectric layer can have a thickness than is less than λ. In some embodiments, the acoustic wave device can include a temperature compensating layer that is disposed between the piezoelectric layer and the spinel layer.

An acoustic wave filter includes a substrate and a piezoelectric layer over the substrate. First acoustic wave resonators are disposed over the piezoelectric layer and arranged in series along a first branch, and second acoustic wave resonators are disposed over the piezoelectric layer, arranged in parallel, and connected to the first branch and to ground. The first and second acoustic wave resonators include an interdigital transducer electrode interposed between a pair of reflectors. The interdigital transducer electrode of one or more of the second plurality of acoustic wave resonators has a wider duty factor than the interdigital transducer electrodes of the first plurality of acoustic wave resonators.

An acoustic wave filter includes a substrate and a piezoelectric layer over the substrate. First acoustic wave resonators are disposed over the piezoelectric layer and arranged in series along a first branch, and second acoustic wave resonators are disposed over the piezoelectric layer, arranged in parallel, and connected to the first branch and to ground. The first and second acoustic wave resonators include an interdigital transducer electrode interposed between a pair of reflectors. A layer of positive temperature coefficient of frequency dielectric material is disposed over one or more of the first plurality of acoustic wave resonators to control the temperature coefficient of frequency and improve temperature stability of the acoustic wave filter.

Aspects of this disclosure relate to an acoustic wave resonator having at least two resonant frequencies. An acoustic wave filter can include series acoustic wave resonators and shunt acoustic wave resonators together arranged to filter a radio frequency signal. A first shunt resonator of the shunt acoustic wave resonators can include an interdigital transducer electrode and have at least a first resonant frequency and a second resonant frequency. Related acoustic wave resonators, multiplexers, wireless devices, and methods are disclosed.

An acoustic wave device includes a piezoelectric layer made of lithium niobate or lithium tantalate, and at least one pair of electrodes opposed to each other in a direction intersecting a thickness direction of the piezoelectric layer. When d is a thickness of the piezoelectric layer and p is a distance between centers of electrodes adjacent to each other in the at least one pair of electrodes, d/p is about 0.5 or less. The at least one pair of electrodes extend in a longitudinal direction and includes a first electrode and a second electrode with sectional shapes different from each other in any cross section in a direction orthogonal or substantially orthogonal to the longitudinal direction of the at least one pair of electrodes.