Aspects of this disclosure relate to acoustic wave devices on stacked die. A first die can include first acoustic wave device configured to generate a boundary acoustic wave. A second die can include a second acoustic wave device configured to generate a second boundary acoustic wave, in which the second die is stacked with the first die. The first acoustic wave resonator can include a piezoelectric layer, an interdigital transducer electrode on the piezoelectric layer, and high acoustic velocity layers on opposing sides of the piezoelectric layer. The high acoustic velocity layers can each have an acoustic velocity that is greater than a velocity of the boundary acoustic wave.

Aspects of this disclosure relate to an acoustic wave device that includes high velocity layers on opposing sides of a piezoelectric layer. A low velocity layer can be positioned between the piezoelectric layer and one of the high velocity layers, in which the low velocity layer has a lower acoustic velocity than the high velocity layers. The acoustic wave device can be configured to generate a boundary acoustic wave such that acoustic energy is concentrated at a boundary of the piezoelectric layer and the low velocity layer.

The present application is directed to a MEMS device. The MEMS device includes a substrate having a first end and a second end extending along a longitudinal axis, the substrate including an electrostatic actuator. The device also includes a movable plate having a first end and a second end. The device also includes a thermal actuator having a first end coupled to the first end of the substrate and a second end coupled to the first end of the plate. The actuator moves the plate in relation to the substrate. Further, the device includes a power source electrically coupled to the thermal actuator and the substrate. The application is also directed to a method for operating a MEMS device.

A method of an open loop characterization of an electrostatic MEMS based resonator with a varying gap, the method including: converting, via a trans-impedance amplifier circuit, an output current signal of the resonator into a voltage; multiplying the output current signal converted into the voltage, by means of a multiplier circuit, with an AC signal or with a different signal at a frequency of the resonator and carrying a second harmonic signal to a main tone; and measuring a frequency response of a signal cleared of frequencies apart from the main tone using a network analyzer.

A radio frequency (RF) front-end (RFFE) device includes a die having a front-side dielectric layer on an active device. The active device is on a first substrate. The RFFE device also includes a microelectromechanical system (MEMS) device. The MEMS device is integrated on the die at a different layer than the active device. The MEMS device includes a cap layer composed of a cavity in the front-side dielectric layer of the die. The cavity in the front-side dielectric layer is between the first substrate and a second substrate. The cap is coupled to the front-side dielectric layer.

Non-transitory computer-readable media to perform a method for designing a multiband filter. The method includes generating an initial circuit structure comprising a desired number and type of circuit elements; generating an initial circuit design by mapping the frequency response requirements of the initial circuit structure into normalized space; generating an acoustic filter circuit design by transferring the initial filter circuit design; generating a pre-optimized circuit design by unmapping one or more circuit elements of the acoustic filter circuit design into real space and introducing parasitic effects; and communicating the pre-optimized circuit design to a filter optimizer that generates a final circuit design comprising a plurality of resonators, wherein a first resonator exhibits a high resonant frequency, a second resonator demonstrates a low resonant frequency and the difference between the low resonant frequency and the high resonant frequency is at least 1.25 times the average frequency separation of the resonators.

A method of designing an acoustic microwave filter comprises generating a proposed filter circuit design having an acoustic resonant element with a defined admittance value, introducing a lumped capacitive element in parallel and a lumped inductive element in series with the resonant element, selecting a first capacitance value for the capacitive element and a first inductance value for the inductive element, thereby creating a first temperature modeled filter circuit design, simulating the first temperature modeled filter circuit design at a first operating temperature, thereby generating a first frequency response, selecting a second capacitance value for the capacitive element and a second inductance value for the inductive element, thereby creating a second temperature modeled filter circuit design, simulating the second temperature modeled filter circuit design at a second operating temperature, thereby generating a second frequency response, and comparing the first and second frequency responses to the frequency response requirements.

Active feedback is used with two electrodes of a four-electrode capacitive-gap transduced wine-glass disk resonator to enable boosting of an intrinsic resonator Q and to allow independent control of insertion loss across the two other electrodes. Two such Q-boosted resonators configured as parallel micromechanical filters may achieve a tiny 0.001% bandwidth passband centered around 61 MHz with only 2.7 dB of insertion loss, boosting the intrinsic resonator Q from 57,000, to an active Q of 670,000. The split capacitive coupling electrode design removes amplifier feedback from the signal path, allowing independent control of input-output coupling, Q, and frequency. Controllable resonator Q allows creation of narrow channel-select filters with insertion losses lower than otherwise achievable, and allows maximizing the dynamic range of a communication front-end without the need for a variable gain low noise amplifier.

A filter includes two series arm resonators electrically connected in series between two input/output terminals, a parallel arm resonator electrically connected between a ground and a series arm between the two series arm resonators, an inductor electrically connected in parallel to the two series arm resonators, and a matching circuit electrically connected between one of the two series arm resonators and one of the input/output terminals, wherein the two series arm resonators and the parallel arm resonator define a pass band of a bandpass filter, the two series arm resonators and the inductor define an LC resonant circuit, respective anti-resonant frequencies of each of the two series arm resonators and a resonant frequency of the parallel arm resonator are located in a pass band of the LC resonant circuit, and a resonant frequency of the LC resonant circuit is lower than the resonant frequency of the parallel arm resonator.

Embodiments of a tunable bandpass microelectromechanical (MEMS) filter are described. In one embodiment, such a filter includes a pair of arch beam microresonators, and a pair of voltage sources electrically coupled to apply a pair of adjustable voltage biases across respective ones of the pair of arch beam microresonators. The pair of voltage sources offer independent tuning of the bandwidth of the filter. Based on the structure and arrangement of the filter, it can be tunable by 125% or more by adjustment of the adjustable voltage bias. The filter also has a relatively low bandwidth distortion, can exhibit less than 2.5 dB passband ripple, and can exhibit sideband rejection in the range of at least 26 dB.