An integrated radio frequency (RF) circuit combines complementary features of passive devices and acoustic filters and includes a first die, a second die, and a third die. The first die includes a substrate having one or more passive devices. The second die includes a first acoustic filter. The second die is stacked and coupled to a first surface of the first die. The third die includes a second acoustic filter. The third die is stacked and coupled to a second surface opposite the first surface of the first die.

An acoustic wave device includes a supporting substrate, an acoustic reflection film the supporting substrate, a piezoelectric thin film on the acoustic reflection film, and an interdigital transducer electrode the piezoelectric thin film. The acoustic reflection film includes acoustic impedance layers including therein first, second, third, and fourth low acoustic impedance layers and first, second, and third high acoustic impedance layers. The acoustic reflection film includes a first acoustic impedance layer and a second acoustic impedance layer, the first and second acoustic impedance layers each being one of the acoustic impedance layers, and the second acoustic impedance layer has an arithmetic average roughness different from that of the first acoustic impedance layer.

Embodiments may relate to a radio frequency (RF) front-end module (FEM) with a first filter and a second filter. The RF FEM may include a termination inductor coupled to ground, and a switch that is to selectively couple the first filter and the second filter to the termination inductor. Other embodiments may be described or claimed.

A semiconductor package includes a main substrate, a resonator device disposed above the main substrate, a wiring portion connected to the resonator device, an electrical connection structure connected to the wiring portion and the main substrate, an encapsulant encapsulating the resonator device and the electrical connection structure, and a heat dissipation member bonded to and mounted on the resonator device. A cavity is provided in the resonator device, and is formed between the resonance portion and a resonator device substrate provided in the resonator device.

Reduced-size guided-surface acoustic wave (SAW) resonators are disclosed. Guided-SAW resonators can achieve high acoustic coupling and acoustic quality Q, but may have a larger surface area compared with a traditional temperature compensated (TC)-SAW resonator. In an exemplary aspect, a guided-SAW device is fabricated with a metal-insulator-metal (MIM) capacitor to produce a guided-SAW which has the same high Q with a surface area which is the same or less than traditional TC-SAW resonators.

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.

An acoustic wave device includes a support substrate including a main surface including first and second regions adjacent to each other in a plan view; a multilayer body including an intermediate layer in the first region of the support substrate and a piezoelectric layer on the intermediate layer, and including a side surface; an IDT electrode on the piezoelectric layer of the multilayer body; and an insulating film in the second region of the support substrate to cover the side surface of the multilayer body. An angle defined between the main surface of the support substrate and the side surface of the multilayer body is a tilt angle, and the side surface of the multilayer body includes portions having different tilt angles at a portion covered with the insulating film.

A resonator device may include a stacked first resonator and second resonator. The first resonator may be configured to resonate at a first operating frequency, and the second resonator may be configured to resonate at a second operating frequency different from the first operating frequency. The first resonator may include a first electrode and a first active layer arranged over the first electrode. The second resonator may include a second active layer arranged over the first active layer, and a second electrode arranged over the second active layer. The stacked first resonator and second resonator may be coupled to a reconfiguration switch for selectively operating at the first operating frequency or the second operating frequency. One of the first resonator and the second resonator is active upon selection by the reconfiguration switch, while the other resonator is inactive.

An elastic wave device includes an impedance matching element, a switch that switches a connection state between a first switch terminal connected to the impedance matching element and second switch terminals, multiplexers connected to the second switch terminals, a substrate, and at least one inductor on the substrate and has an inductance smaller than an inductance of the impedance matching element. At least one of the second switch terminals and at least one of the multiplexers are connected with the first inductor interposed therebetween.

Unreleased plane acoustic wave (PAW) resonators are disclosed. An example unreleased PAW resonator includes a substrate, a first acoustic reflector disposed on the substrate, and a piezoelectric layer disposed on the first acoustic reflector, wherein the first acoustic reflector and the piezoelectric layer are unreleased from the substrate.