In an acoustic wave device, a piezoelectric body is directly or indirectly provided on a high acoustic velocity material layer, an interdigital transducer electrode is directly or indirectly provided on the piezoelectric body, the interdigital transducer electrode includes a first busbar, a second busbar spaced away from the first busbar, a plurality of first electrode fingers, and a plurality of second electrode fingers, and a weighting is applied to the interdigital transducer electrode by providing a floating electrode finger not electrically connected to the first busbar or the second busbar or applied by providing an electrode finger formed by metallizing a gap between the first electrode fingers or a gap between the second electrode fingers to integrate the first electrode fingers or the second electrode fingers.

An acoustic wave device has a substrate, an optional functional layer disposed over at least a portion of the substrate, a piezoelectric layer disposed over at least a portion of the functional layer and/or substrate, and an interdigital transducer electrode disposed on the piezoelectric layer. The piezoelectric layer has an outer edge spaced inward of an outer edge of the substrate, the outer edge of the piezoelectric layer being tapered at an angle relative to a surface of the substrate to thereby reduce an acoustic reflection magnitude at said outer edge of the piezoelectric layer.

An acoustic wave element includes an IDT electrode including a plurality of electrode fingers and exciting a surface acoustic wave, a first substrate including an upper surface on which the IDT electrode is located, the first substrate being configured by a piezoelectric crystal, and a second substrate bonded to a side where a lower surface of the first substrate is located. Either of a first region which continues from the lower surface of the first substrate toward a side where the upper surface is located or a second region which continues from the lower surface of the first substrate toward a side where the second substrate is located is a low resistance region having a resistance value of 5×10.sup.3Ω to 5×10.sup.7Ω.

Acoustic wave resonators are disclosed that include a piezoelectric layer and an interdigital transducer electrode over the piezoelectric layer. The interdigital transducer electrode has a rotation angle and a tilt angle. The rotation angle and the tilt angle can together increase a figure of merit of the acoustic wave device. The rotation angle and the tilt angle can both be non-zero.

A filter device, an RF front-end device and a wireless communication device are provided. The filter device includes a substrate, a passive device and at least one resonance device, wherein the passive device has a first side and a second side opposite to the first side, the substrate is located on the first side, and the at least one resonance device is located on the second side. The RF filter device formed by integrating the resonance device (such as an SAW or BAW resonance device) and the passive device (such as an IPD) can broaden the pass-band width, has a high out-of-band rejection, and occupies less space in an RF front-end chip.

An acoustic wave device assembly is disclosed. The acoustic wave device assembly can include a first acoustic wave device that includes a first substrate, a first piezoelectric layer, a first solid acoustic mirror that is disposed between the first substrate and the first piezoelectric layer, and a first interdigital transducer electrode that has a first portion embedded in the first piezoelectric layer and a second portion disposed over a surface of the first piezoelectric layer. The acoustic wave device assembly can include a second acoustic wave device that includes a second substrate, a second piezoelectric layer, a second solid acoustic mirror that is disposed between the second substrate and the second piezoelectric layer, and a second interdigital transducer electrode that is in contact with the second piezoelectric layer. The second acoustic wave device is stacked over the first acoustic wave device. The first acoustic wave device and the second acoustic wave device are spaced by a spacer assembly such that a cavity is formed between the first acoustic wave device and the second acoustic wave device.

A stacked acoustic wave device assembly is disclosed. The stacked acoustic wave device assembly can include a first acoustic wave device including a first double acoustic mirror structure having a first solid acoustic mirror and a second solid acoustic mirror, and a first piezoelectric layer between the first and second solid acoustic mirrors. The stacked acoustic wave device assembly can include a second acoustic wave device including a second double acoustic mirror structure having a third solid acoustic mirror and a fourth acoustic mirror, and a second piezoelectric layer between the third and fourth acoustic mirrors. The second acoustic wave device is vertically stacked on the first acoustic wave device such that the second solid acoustic mirror and the fourth solid acoustic mirror are positioned between the first and second piezoelectric layers.

An acoustic wave device is disclosed. The acoustic wave device is configured to generate a surface acoustic wave having a wavelength L. The acoustic wave device can include a piezoelectric layer. The piezoelectric layer has a thickness in a range of 0.1 L to 0.3 L. The acoustic wave device can include an interdigital transducer electrode that is positioned over the piezoelectric layer, and a support substrate that is bonded to the piezoelectric layer such that the piezoelectric layer is positioned between the interdigital transducer electrode and the support substrate. The support substrate has a cut angle configured to provide a velocity of the surface acoustic wave calculated by multiplying the wavelength L by a particular frequency to be greater than 4800 m/s.

An elastic wave device includes an interdigital transducer electrode, a dielectric film, and a frequency adjustment film are disposed on a LiNbO.sub.3 substrate. When Euler Angles of the LiNbO.sub.3 substrate are within a range of about 0°±5°, within a range of about θ±1.5°, within a range of about 0°±10°, the interdigital transducer electrode includes a main electrode, a film thickness of the main electrode normalized by a wavelength determined in accordance with an electrode finger pitch of the interdigital transducer electrode is denoted as T, and a density ratio of a material of the main electrode to Pt is denoted as r, the film thickness of the main electrode and θ of the Euler Angles satisfy θ=−0.05°/(T/r−0.04)+31.35°.

An acoustic wave device includes an element substrate having piezoelectricity, an interdigital transducer electrode provided on the element substrate, and a mold resin covering the element substrate. When viewed in a cross section, the element substrate includes an interdigital transducer formation region in which the interdigital transducer electrode is provided and a pair of interdigital transducer non-formation regions in which the interdigital transducer electrode is not provided and located on both sides of the interdigital transducer formation region, and a thickness dimension of a center portion, in a width direction, of the interdigital transducer formation region is less than at least one of thickness dimensions of center portions, in the width direction, of the interdigital transducer non-formation regions.