A laterally excited bulk acoustic wave device is disclosed. The laterally excited bulk acoustic wave device can include a first solid acoustic mirror, a second solid acoustic mirror, a piezoelectric layer that is positioned between the first solid acoustic mirror and the second solid acoustic mirror, an interdigital transducer electrode on the piezoelectric layer, and a support substrate arranged to dissipate heat associated with the bulk acoustic wave. The interdigital transducer electrode is arranged to laterally excite a bulk acoustic wave. The first solid acoustic mirror and the second solid acoustic mirror are arranged to confine acoustic energy of the bulk acoustic wave. The first solid acoustic mirror is positioned on the support substrate.

A band-pass filter includes a first inductor and a second inductor electromagnetically coupled to each other, a first ground terminal electrically connected to the first inductor, a second ground terminal electrically connected to the second inductor, and a stack for integrating the first inductor, the second inductor, the first ground terminal, and the second ground terminal. The first ground terminal and the second ground terminal are each connected to a ground and are not electrically connected to each other in the stack.

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 multiplexer includes a common terminal, a first terminal, a second terminal, a first filter device including acoustic wave resonators including series resonators and parallel resonators, an inductor provided between an acoustic wave resonator and the first terminal, and a second filter device. The first filter device further includes a first ground terminal to which a parallel resonator is electrically connected, a second ground terminal to which the parallel resonators are electrically connected, and a wiring provided between the inductor and an acoustic wave resonator. In the first filter device, the wiring is electrically connected to the first ground terminal, and the first ground terminal is not connected to the second ground terminal.

A method for fabricating a multi-layer resonator assembly includes sequentially fabricating a plurality of vertically-stacked resonator layers including, for each resonator layer of the plurality of resonator layers, depositing a dielectric layer, forming at least one film bulk acoustic resonator (FBAR) cavity in the deposited dielectric layer, filling each FBAR cavity of the at least one FBAR cavity with a sacrificial material block, and depositing a FBAR material stack over the at least one FBAR cavity. The deposited FBAR material stack is in contact with the sacrificial material block and the dielectric layer. The method further includes removing the sacrificial material block from the at least one FBAR cavity for each resonator layer of the plurality of resonator layers subsequent to sequentially fabricating the plurality of resonator layers.

MEMS based sensors, particularly capacitive sensors, potentially can address critical considerations for users including accuracy, repeatability, long-term stability, ease of calibration, resistance to chemical and physical contaminants, size, packaging, and cost effectiveness. Accordingly, it would be beneficial to exploit MEMS processes that allow for manufacturability and integration of resonator elements into cavities within the MEMS sensor that are at low pressure allowing high quality factor resonators and absolute pressure sensors to be implemented. Embodiments of the invention provide capacitive sensors and MEMS elements that can be implemented directly above silicon CMOS electronics.

A resonator device includes: a resonator element; a heat generating unit; a first package including a first base at which the resonator element and the heat generating unit are disposed, and a first lid bonded to the first base so as to accommodate the resonator element between the first lid and the first base; and a low emissivity layer that is disposed at an inner surface of the first lid and that has an emissivity lower than an emissivity of the first lid. In addition, a constituent material of the first lid is silicon, and the emissivity of the low emissivity layer at room temperature is less than 0.5.

MEMS based sensors, particularly capacitive sensors, potentially can address critical considerations for users including accuracy, repeatability, long-term stability, ease of calibration, resistance to chemical and physical contaminants, size, packaging, and cost effectiveness. Accordingly, it would be beneficial to exploit MEMS processes that allow for manufacturability and integration of resonator elements into cavities within the MEMS sensor that are at low pressure allowing high quality factor resonators and absolute pressure sensors to be implemented. Embodiments of the invention provide capacitive sensors and MEMS elements that can be implemented directly above silicon CMOS electronics.

A surface acoustic wave (SAW) filter includes a filter wafer including: a first substrate; and an interdigital transducer (IDT) disposed on the first substrate, the IDT including a first input and output end, a second input and output end, and an interdigital portion. The SAW filter also includes a dielectric layer disposed on the filter wafer, covering the first input and output end and the second input and output end of the IDT and exposing the interdigital portion; a passivation layer disposed on the dielectric layer; a bonding layer disposed on the passivation layer; a second substrate bonded to the filter wafer via the bonding layer; and a cavity enclosed by the second substrate and the bonding layer.

A bulk-acoustic resonator module includes: a module substrate; a bulk-acoustic resonator connected to the module substrate by a connection terminal and disposed spaced apart from the module substrate; and a sealing portion sealing the bulk-acoustic resonator. The bulk-acoustic resonator includes a resonating portion disposed opposite to an upper surface of the module substrate. A space is disposed between the resonating portion and the upper surface of the module substrate.