An elastic wave device includes a piezoelectric substrate and IDT electrodes including first and second busbars and first and second electrode fingers. An intersection of the IDT electrodes includes a center region, and low-acoustic-velocity sections at both end portions of the center region in the direction in which the electrode fingers extend in the center region, sections in which the acoustic velocity is lower than in the center region. The length of the gap between the edge of the first electrode fingers and the second busbar and the length of the gap between the edge of the second electrode fingers and the first busbar are about 0.62 or more and about 0.98 or less, where denotes the wavelength, which is determined by the finger pitch of the IDT electrodes.

A SAW device includes a SAW element, a conductor connected to the SAW element, an LT substrate including the SAW element, and a case for housing the LT substrate including the SAW element. The case includes a cover part, a lateral part, and a bottom part. The bottom part is including a sapphire substrate, the LT substrate is positioned on a first surface of the sapphire substrate, the first surface serving as an inner surface of the case, and a second surface opposite to the first surface serves as an outer surface of the case. The conductor includes a via conductor provided in a through-hole continuously penetrating through the sapphire substrate and the LT substrate.

Due to strong needs to reduce the dimensions and the cost of the RF filters and to reduce the number of filters required in an mobile handsets and wireless system covering numbers of operation bands, tunable RF filters which can cover as many bands or frequency ranges as possible are needed so that the number of filters can be reduced in the mobile handsets and wireless systems. The present invention provides tunable surface acoustic wave (SAW) IDT structures with the resonant frequency of the acoustic wave to be excited and to be transmitted tuned by digital to analog converters (DACs). The DAC converts an input digital signal to an output DC voltage and provide DC bias voltages to the SAW IDTs through integrated thin film biasing resistors. The polarity and the value of the output DC voltage are controlled by the input digital signal to achieve selection and tuning of the resonant frequency of the SAW IDTs.

An acoustic wave filter includes a series-arm resonator, a first parallel-arm resonator, and a second parallel-arm resonator. The series-arm resonator is disposed on a path connecting first and second input/output terminals. The first parallel-arm resonator is disposed on a path that connects ground with a node, which is located on a path connecting the series-arm resonator with the first input/output terminal. The second parallel-arm resonator is disposed on a path that connects ground with a node, which is located on a path connecting the series-arm resonator with the second input/output terminal. The parallel-arm resonator has a resonant frequency lower than the resonant frequency of the second parallel-arm resonator. The first parallel-arm resonator has an anti-resonant frequency higher than the anti-resonant frequency of the second parallel-arm resonator. The second parallel-arm resonator has the highest resonant frequency of all the parallel-arm resonators.

A multiplexer includes a first reception-side filter and a second reception-side filter whose passband has frequencies higher than the first reception-side filter. The first reception-side filter includes a series arm resonator provided on a first path, and parallel arm resonators provided on a path electrically connecting the first path and ground. A direction connecting tips of a plurality of electrode fingers included in each resonator crosses an elastic wave propagating direction at a certain angle. The parallel arm resonator closest to a common connection terminal does not include third electrode fingers, and the other parallel arm resonators include third electrode fingers.

A product disclosed herein includes an RF filter die including an RF filter, a front side and a plurality of conductive bond pads conductively coupled to at least a portion of the RF filter, wherein at least a portion of the conductive bond pads is exposed on the front side of the RF filter die. The product also includes a TSV (Through-Substrate-Via) die that includes a plurality of conductive TSV contacts positioned on a back side of the TSV die and at least one conductive TSV (Through-Substrate-Via) structure that is conductively coupled to at least one of the plurality of conductive TSV contacts, wherein the back side of the TSV die is bonded to the front side of the RF filter such that the conductive bond pads on the RF filter die are conductively coupled to corresponding conductive TSV contacts positioned on the back side of the TSV die.

In a method of manufacturing a piezoelectric device, among a +C plane on a +Z axis side of a piezoelectric thin film and a C plane on a Z axis side of the piezoelectric thin film, the C plane on the Z axis side of the piezoelectric thin film is etched. Thus, Z planes of the piezoelectric thin film on which epitaxial growth is possible are exposed. Ti is epitaxially grown on the Z planes of the piezoelectric thin film in the Z axis direction such that the crystal growth plane thereof is parallel to the Z planes of the piezoelectric thin film. Al is then epitaxially grown on the surface of the Ti electrode in the Z axis direction such that the crystal growth plane thereof is parallel to the Z planes of the piezoelectric thin film.

Due to strong needs to reduce the dimensions and the cost of the RF filters and to reduce the number of filters required in an mobile handsets and wireless system covering numbers of operation bands, tunable RF filters which can cover as many bands or frequency ranges as possible are needed so that the number of filters can be reduced in the mobile handsets and wireless systems. The present invention provides tunable surface acoustic wave (SAW) IDT structures with the resonant frequency of the acoustic wave to be excited and to be transmitted tuned by digital to analog converters (DACs). The DAC converts an input digital signal to an output DC voltage and provide DC bias voltages to the SAW IDTs through integrated thin film biasing resistors. The polarity and the value of the output DC voltage are controlled by the input digital signal to achieve selection and tuning of the resonant frequency of the SAW IDTs.

An elastic wave element having a piezoelectric substrate equipped with a first main surface, and an excitation electrode arranged on the first main surface and having multiple electrode fingers, wherein, in a cross-sectional view in the direction orthogonal to the first main surface, the width of the electrode fingers at a first height at a distance from the first main surface is greater than the width at a second height located closest to the first main surface.

A surface acoustic wave (SAW) device including a piezoelectric layer, a high acoustic velocity layer coupled to the piezoelectric layer, and at least one transducer. The SAW device may include a multi-layer graphene layer in the electrodes of the transducer and/or in a conductive layer that is coupled to the piezoelectric layer.