A resonator has a resonator body and a frame at least partially surrounding the resonator body, the resonator body being coupled to the frame by at least one tether. The resonator body, frame and at least one tether comprise silicon carbide. A plurality of interdigitated electrodes are disposed on the silicon carbide resonator body. The resonator body preferably comprises 6H silicon carbide and preferably has a crystalline c-axis oriented generally parallel to a thickness direction of the resonator body.

A filter includes a piezoelectric film including lithium niobate or lithium tantalate, an acoustic wave resonator including a functional electrode on the piezoelectric film, a capacitor on the piezoelectric film and connected in parallel to the acoustic wave resonator, and a resonator electrically connected to the acoustic wave resonator. The functional electrode includes a pair of first and second electrodes facing each other in a direction intersecting a thickness direction of the piezoelectric film. When a thickness of the piezoelectric film is d and a center-to-center distance between the first electrode and the second electrode is p, d/p is smaller than or equal to about 0.5.

An acoustic wave device includes a support with a thickness in a first direction, a piezoelectric layer extending on the support in the first direction, and an interdigital transducer electrode on a principal surface of the piezoelectric layer. The interdigital transducer electrode includes first electrode fingers extending in a second direction crossing the first direction, a first busbar electrode connected to the first electrode fingers, second electrode fingers extending in the second direction and facing corresponding ones of the first electrode fingers in a third direction perpendicular or substantially perpendicular to the second direction, and a second busbar electrode connected to the second electrode fingers. The piezoelectric layer includes a piezoelectric multilayer structure in a gap region between at least one first electrode finger and the second busbar electrode, or between at least one second electrode finger and the first busbar electrode, in plan view in the first direction. The piezoelectric multilayer structure includes first and second piezoelectric bodies with different dielectric polarizations.

Resonator devices, filter devices, and methods of fabrication are disclosed. A resonator device includes a substrate and a single-crystal piezoelectric plate having front and back surfaces. An acoustic Bragg reflector is sandwiched between a surface of the substrate and the back surface of the piezoelectric plate. An interdigital transducer (IDT) is formed on the front surface of the piezoelectric plate. The IDT and the piezoelectric plate are configured such that a radio frequency signal applied to the IDT excites a primary acoustic mode within the piezoelectric plate. The acoustic Bragg reflector comprises alternating SiO.sub.2 and diamond layers and is configured to reflect the primary acoustic mode.

A multi-stage matching network filter circuit device. The device comprises bulk acoustic wave (BAW) resonator device having an input node, an output node, and a ground node. A first matching network circuit is coupled to the input node. A second matching network circuit is coupled to the output node. A ground connection network circuit coupled to the ground node. The first or second matching network circuit can include an inductive ladder network including a plurality of series inductors in a series configuration and a plurality of grounded inductors wherein each of the plurality of grounded inductors is coupled to the connection between each connected pair of series inductors. The inductive ladder network can include one or more LC tanks, wherein each of the one or more LC tanks is coupled between a connection between a series inductor and a subsequent series inductor, which is also coupled to a grounded inductor.

A method of wafer scale packaging acoustic resonator devices and an apparatus therefor. The method including providing a partially completed semiconductor substrate comprising a plurality of single crystal acoustic resonator devices, each having a first electrode member, a second electrode member, and an overlying passivation material. At least one of the devices to be configured with an external connection, a repassivation material overlying the passivation material, an under metal material overlying the repassivation material. Copper pillar interconnect structures are then configured overlying the electrode members, and solder bump structures are form overlying the copper pillar interconnect structures.

A substrate includes a substrate main body that includes a first main surface and a second main surface facing the first main surface. First electrode lands are disposed inside a recessed portion of the first main surface of the substrate main body. Second electrode lands are disposed in a region outside the recessed portion. The first electrode land and the second electrode land are connected to different electric potentials.

Radio frequency filters are disclosed. A filter includes a first transversely-excited film bulk acoustic resonator (XBAR) having a first sub-resonator and a second sub-resonator connected in parallel. A pitch of the first sub-resonator is not equal to a pitch of the second sub-resonator and/or a mark of the first sub-resonator is not equal to a mark of the second sub-resonator.

Resonator and filter devices and methods of fabrication. A resonator chip includes a substrate, a piezoelectric plate, and an acoustic Bragg reflector between the substrate and a back surface of the piezoelectric plate. A conductor pattern on a front surface of the piezoelectric plate includes a first plurality of contact pads and an interdigital transducer (IDT). The IDT and the piezoelectric plate are configured such that a radio frequency signal applied to the IDT excites a shear primary acoustic mode within the piezoelectric plate. The acoustic Bragg reflector is configured to reflect the shear primary acoustic mode. An interposer has a second plurality of contact pads on a back surface. A seal connects a perimeter of the piezoelectric plate to a perimeter of the interposer. Each contact pad of the first plurality of contact pads is directly connected to a respective contact pad of the second plurality of contact pads.

A piezoelectric film that includes crystalline AlN; at least one first element partially replacing Al in the crystalline AlN; and a second element doping the crystalline AlN and which has an ionic radius smaller than that of the first element and larger than that of Al.