A crystal oscillator includes a piezoelectric substrate, a first electrode, a second electrode, and a support frame. The first electrode includes a first electrode portion disposed on a first surface of the piezoelectric substrate. The second electrode is disposed on a second surface of the piezoelectric substrate opposite to the first surface of the piezoelectric substrate. The support frame is made of a photoresist material, and is disposed on the second surface. The support frame surrounds the second electrode portion. At least a portion of the second extending electrode portion is located outside the support frame. A method for making the crystal oscillator is also provided herein.

A crystal oscillator includes an oscillating substrate, a hollow frame, a first electrode, and a second electrode. The oscillating substrate includes a main oscillating region and a thinned region that has a thickness smaller than that of the main oscillating region. The first and second electrodes are disposed on a first surface of the oscillating substrate and a second surface opposite to the first surface, respectively. The hollow frame is disposed on the second surface. The second electrode includes a second electrode portion that has at least one opening in positional correspondence with the thinned region. A method for making the crystal oscillator is also provided herein.

A MEMS device is provided that includes a piezoelectric film, a first electrode and a second electrode sandwiching the piezoelectric film, a protective film that covers at least part of the second electrode and having a cavity that opens part of the second electrode, a third electrode that contacts the second electrode at least in the cavity and is provided so as to cover at least part of the protective film, and a first wiring layer having a first contact portion in contact with the third electrode.

A system for a wireless communication infrastructure using single crystal devices. The wireless system can include a controller coupled to a power source, a signal processing module, and a plurality of transceiver modules. Each of the transceiver modules includes a transmit module configured on a transmit path and a receive module configured on a receive path. The transmit modules each include at least a transmit filter having one or more filter devices, while the receive modules each include at least a receive filter. Each of these filter devices includes a single crystal acoustic resonator device formed with a thin film transfer process with at least a first electrode material, a single crystal material, and a second electrode material. Wireless infrastructures using the present single crystal technology perform better in high power density applications, enable higher out of band rejection (OOBR), and achieve higher linearity as well.

A vibration-absorbing structure for packaging a crystal resonator includes a package base, a resonant crystal blank, and a top cover. The top of the package base has a recess. The sidewall of the package base surrounds the recess. The resonant crystal blank has a border area, at least one serpentine connection area, and a resonant area. The serpentine connection area is connected between the border area and the edge of the resonant area. The border area is arranged on the sidewall. The top cover, arranged on the border area, covers the recess, the at least one serpentine connection area, and the resonant area.

An RF filter system including a plurality of BAW resonators arranged in a circuit, the circuit including a serial configuration of resonators and a parallel shunt configuration of resonators, the circuit having a circuit response corresponding to the serial configuration and the parallel configuration of the plurality of bulk acoustic wave resonators including a transmission loss from a pass band having a bandwidth from 5.170 GHz to 5.835 GHz. Resonators include a support member with a multilayer reflector structure; a first electrode including tungsten; a piezoelectric film including aluminum scandium nitride; a second electrode including tungsten; and a passivation layer including silicon nitride. At least one resonator includes at least a portion of the first electrode located within a cavity region defined by a surface of the support member.

A crystal resonator includes: lower glass plates on which first electrodes are formed so as to extend from side surfaces to a bottom surface of the lower glass plates; a crystal plate which is provided over the lower glass plates and on which second electrodes to be coupled to the first electrodes are formed on a surface in contact with the lower glass plates; and an upper glass plate which is provided over the crystal plate; wherein the side surfaces of the lower glass plates on which the first electrodes are formed are provided with a protrusion that extends in parallel with a top surface and the bottom surface of the lower glass plates and that extends from one end to the other end of each of the side surfaces, and wherein the first electrodes are formed on the side surfaces that include surfaces of the protrusion.

An RF triplexer circuit device using modified lattice, lattice, and ladder circuit topologies. The devices can include four resonator devices and four shunt resonator devices. In the ladder topology, the resonator devices are connected in series from an input port to an output port while shunt resonator devices are coupled the nodes between the resonator devices. In the lattice topology, a top and a bottom serial configurations each includes a pair of resonator devices that are coupled to differential input and output ports. A pair of shunt resonators is cross-coupled between each pair of a top serial configuration resonator and a bottom serial configuration resonator. The modified lattice topology adds baluns or inductor devices between top and bottom nodes of the top and bottom serial configurations of the lattice configuration. These topologies may be applied using single crystal or polycrystalline bulk acoustic wave (BAW) resonators.

A film bulk acoustic resonator (FBAR) structure includes a bottom cap wafer, a piezoelectric layer disposed on the bottom cap wafer, a bottom electrode disposed below the piezoelectric layer, and a top electrode disposed above the piezoelectric layer. Portions of the bottom electrode, the piezoelectric layer, and the top electrode that overlap with each other constitute a piezoelectric stack. The FBAR structure further includes a lower cavity disposed below the piezoelectric stack. A projection of the piezoelectric stack is located within the lower cavity.

A method and structure for a transfer process for an acoustic resonator device. In an example, a bulk acoustic wave resonator (BAWR) with an air reflection cavity is formed. A piezoelectric thin film is grown on a crystalline substrate. One or more patterned electrodes are deposited on the surface of the piezoelectric film. An etched sacrificial layer is deposited over the one or more electrodes and a planarized support layer is deposited over the sacrificial layer. The support layer is etched to form one or more cavities overlying the electrodes to expose the sacrificial layer. The sacrificial layer is etched to release the cavities around the electrodes. Then, a cap layer is fusion bonded to the support layer to enclose the electrodes in the support layer cavities.