Abstract: A variable frequency filter includes a series arm resonant circuit and first and second parallel arm resonant circuits. The series arm resonant circuit is connected between a first connection terminal and a second connection terminal. The first parallel arm resonant circuit is connected to the first connection terminal side of the series arm resonant circuit. In the first parallel arm resonant circuit, a first piezoelectric resonator and a variable capacitor are connected in series to each other. The second parallel arm resonant circuit is connected to the second connection terminal side of the series arm resonant circuit. In the second parallel arm resonant circuit, a second piezoelectric resonator and a variable capacitor are connected in series to each other. The impedance of the first piezoelectric resonator is lower than the impedance of the second piezoelectric resonator. The series arm resonant circuit includes a characteristic adjusting capacitor at the first connection terminal side.

Abstract: A multiplexer includes: first and second substrate respectively having first and second surfaces facing each other across an air gap; a first filter including first resonators located on the first surface and connected between a common terminal and a first terminal; a second filter including second resonators located on the second surface and connected between the common terminal and a second terminal, a first resonator connected in series between the common terminal and the first terminal and closest to the common terminal overlapping with a second resonator connected in series between the common terminal and the second terminal and closest to the common terminal, first resonators other than the first resonator closest to the common terminal not overlapping with the second resonators, second resonators other than the second resonator closest to the common terminal not overlapping with the first resonators.

Abstract: An elastic wave apparatus includes a multilayer substrate, first through fourth band pass filters, an antenna terminal, and first and second inductors. The multilayer substrate includes first through sixth wiring layers. The first through fourth band pass filters are disposed on the multilayer substrate and are connected to a common node. The antenna terminal is connected to an antenna and also to the common node. The first inductor is connected to the antenna terminal. The second inductor is connected between the first band pass filter and the common node. The first inductor is disposed on the fourth and fifth wiring layers. The second inductor is disposed on the second and third wiring layers which are different from the fourth and fifth wiring layers. The first and second inductors overlap each other at least partially as viewed from above.

Abstract: An elastic wave device includes an IDT electrode and an insulating film on a piezoelectric substrate. Above an intersection region of the IDT electrode, when one end in an elastic-wave propagation direction is a first end portion and the other end in the elastic-wave propagation direction is a second end portion, the thickness of the insulating film is decreased or increased towards a center in the elastic-wave propagation direction from the first end portion and the second end portion.

Abstract: A bulk acoustic wave resonator includes a substrate including a cavity groove, a membrane layer disposed above the substrate and including a convex portion. And a lower electrode including a portion thereof disposed on the convex portion. The bulk acoustic wave resonator also includes a piezoelectric layer configured so that a portion of the piezoelectric layer is disposed above the convex portion, and an upper electrode disposed on the piezoelectric layer. A first space formed by the cavity groove and a second space formed by the convex portion form a cavity, the cavity groove is disposed below an active region, and the convex portion comprises an inclined surface disposed outside of the cavity groove.

Abstract: In a resonator, two interdigital transducers (W1,W2) are electrically series-connected and arranged next to each other in the longitudinal direction within an acoustic track delimited by reflectors. Between the two interdigital transducers, a transition area (UEB) is formed in that the finger period p, which is defined as the distance between the finger centers of adjacent transducer fingers, is higher in comparison to the remaining interdigital transducer.

Abstract: A surface acoustic wave (SAW) resonator device includes a semiconductor substrate having a first surface and a second surface. The semiconductor substrate comprises a bulk region, and a surface region. The surface region has a high trap density, and a reduced carrier mobility, compared to the bulk region. A piezoelectric layer, having a first surface and a second surface, is disposed over the semiconductor substrate. A plurality of electrodes are disposed over the first surface of the piezoelectric layer, and the plurality of electrodes are configured to generate surface acoustic waves in the piezoelectric layer. The SAW resonator device also comprises a layer disposed between the first surface of the semiconductor substrate and the second surface of the piezoelectric layer.

Abstract: A bulk acoustic wave (BAW) resonator includes: a substrate; a first BAW resonator including a first air cavity disposed in the substrate, and further including a first electrode, a first piezoelectric layer, and a second electrode stacked on the first air cavity; a second BAW resonator including a second air cavity disposed in the substrate, and further including a first electrode, a second piezoelectric layer, and a second electrode stacked on the second air cavity, wherein the second BAW resonator is connected in parallel to the first BAW resonator and has polarities that are opposite of polarities of the first BAW resonator; and a compensation capacitor circuit connected between the first BAW resonator and the second BAW resonator.

Abstract: Multiplexers having hybrid circuits with resonators. In some embodiments, a multiplexer for processing radio-frequency signals can include a plurality of nodes, a common node, and a signal path implemented between each of the plurality of nodes and the common node. Each signal path can include a filter, and each of at least some of the signal paths can further include a resonator coupled with the corresponding filter. A signal path with the resonator provides a sharper notch profile for a radio-frequency signal than a signal path without the resonator.

Abstract: An acoustic wave device includes a plurality of serial resonators and a plurality of parallel resonators configured by acoustic wave elements, which plurality of serial resonators and plurality of parallel resonators configure a filter in which they are connected in a ladder configuration; a first capacitance part which is connected in parallel to at least one of the plurality of serial resonators; and a second capacitance part which is connected in series to at least one of the plurality of parallel resonators.

Abstract: A surface acoustic wave (SAW) resonator device is disclosed. The SAW resonator has a piezoelectric layer disposed over a semiconductor substrate. The piezoelectric layer has a first surface and a second surface. The polarization axis (C-axis) of the piezoelectric layer is oriented at an angle relative to the second surface of the piezoelectric layer in a range of approximately 0° to approximately 45°. A layer is disposed between the first surface of the semiconductor substrate and the second surface of the piezoelectric layer.

Abstract: 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.

Abstract: A longitudinally coupled resonator elastic wave filter is disposed on a piezoelectric substrate. IDT electrodes include first and second busbars. An inorganic insulating layer is provided on at least one side in a direction perpendicular or substantially perpendicular to an elastic wave propagation direction to cover the first or second busbars, and a first wiring line is disposed on the inorganic insulating layer to extend in the elastic wave propagation direction. A second wiring line three-dimensionally crosses the first wiring line with the inorganic insulating layer interposed therebetween. The first wiring line is connected to busbars, which are connected to the same potential, by extending through the inorganic insulating layer.

Abstract: A surface acoustic wave (SAW) resonator includes a piezoelectric layer disposed over a substrate, and a plurality of electrodes disposed over the first surface of the piezoelectric layer. A layer is disposed between the substrate and the piezoelectric layer. A surface of the layer has a smoothness sufficient to foster atomic bonding between layer and the substrate. A plurality of features provided on a surface of the piezoelectric layer reflects acoustic waves and reduces the incidence of spurious modes in the piezoelectric layer.

Abstract: The present disclosure provides a resonator which resonates in a bulk acoustic wave mode. The resonator includes a resonator body, at least one transducer arm and a substrate. The resonator body is deformed at least along a first direction. The transducer arm is connected to the resonator body along the first direction and includes a base, a piezoelectric layer and an electrode layer. The base includes a first end connected to the resonator body. The piezoelectric layer is disposed above the base but not extended to the resonator body, and the electrode layer is disposed above the piezoelectric layer but not extended to the resonator body. The substrate is for securing the transducer arm such that the resonator body is suspended.

Abstract: A ladder filter includes a piezoelectric substrate, an antenna terminal, a transmission terminal, and ground terminals on the piezoelectric substrate, and IDT electrodes. Each of the IDT electrodes is disposed on the piezoelectric substrate and includes a plurality of electrode fingers and a pair of busbars to which first ends of the plurality of electrode fingers are connected commonly. The IDT electrodes define elastic wave resonators. The ladder filter further includes an interlayer insulating film disposed on at least one of the busbars and a thermally conductive member made of a material with thermal conductivity higher than that of the interlayer insulating film and disposed on the interlayer insulating film. The thermally conductive member is in contact with at least one of the antenna terminal, the transmission terminal, and the ground terminals.

Abstract: A piezoelectric thin film comprises aluminum nitride containing a monad and at least one type among a tetrad and a pentad. The piezoelectric thin film having a large electromechanical coupling factor and a small stiffness.

Abstract: Acoustic resonator devices and filters are disclosed. An acoustic resonator includes a substrate and a piezoelectric plate having parallel front and back surfaces, the back surface attached to the substrate. An interdigital transducer (IDT) is formed on the front surface of the piezoelectric plate such that interleaved fingers of the IDT are disposed on a portion of the piezoelectric plate suspended over a cavity formed in the substrate.

Abstract: A micro-resonator includes a first electrode positioned on a piezoelectric plate at a first end of the piezoelectric plate, the first electrode including a first set of fingers and a second electrode positioned on the piezoelectric plate at a second end of the piezoelectric plate. The second electrode including a second set of fingers interdigitated with the first set of fingers with an overlapping distance without touching the first set of fingers, the overlapping distance being less than seven-tenths the length of one of the first set of fingers or the second set of fingers. At least one of the first end or the second end of the piezoelectric plate may define a curved shape.

Abstract: An acoustic wave resonator includes: comb-shaped electrodes located on a piezoelectric substrate, each including electrode fingers exciting an acoustic wave and a bus bar electrode connecting to the electrode fingers, the comb-shaped electrodes forming an overlap region where the electrode fingers of one of the comb-shaped electrodes overlap the electrode fingers of the other, wherein each of the electrode fingers overlapping in the comb-shaped electrodes includes: a first region that is located in the overlap region, where a velocity of the acoustic wave is a first velocity, and of which a position in a first direction in which the electrode fingers extend changes with respect to a second direction intersecting the first direction; and second regions that are located in the overlap region, where a velocity of the acoustic wave is a second velocity different from the first velocity, and that sandwich the first region in the first direction.