Abstract: An acoustic device is provided which comprises an audio system including: a microphone having a microphone output, and a processing circuit having a wakeup input, an audio input, and an audio output, the audio input coupled to the microphone output. In at least one example, the acoustic device further comprises an acoustic sensor separate from the microphone, the acoustic sensor having a sensor output. In at least one example, the acoustic device further comprises a wakeup circuit having a sensor input and a wakeup output, the sensor input coupled to the sensor output, wherein the wakeup output is coupled to the wakeup input.

Abstract: A method comprises: forming a die including a cavity; coupling an anchor to the die; coupling a first resonator to a side of the anchor, in which the first resonator is suspended over the cavity and is operable to bend towards or away from a bottom of the cavity; and coupling a second resonator to the side of the anchor, in which the second resonator is suspended over the cavity, at least a part of the first resonator is laterally between the side of the anchor and a part of the second resonator, and the first resonator is operable to bend in an opposite direction from the second resonator.

Abstract: In some examples, a package includes a semiconductor die having a first surface and a second surface opposing the first surface, the semiconductor die including circuitry in the first surface. The package also includes an acoustic waveguide in the semiconductor die, the acoustic waveguide including an array of capacitors and a connector coupling the circuitry to the acoustic waveguide.

Abstract: A circuit includes a resonator, a transistor pair, and a common-mode feedback circuit. The transistor pair is cross-coupled across the resonator. The common-mode feedback circuit is coupled to the transistor pair. The common-mode feedback circuit includes first and second degeneration cells. The second degeneration cell is connected in parallel with the first degeneration cell. The second degeneration cell is configured to switchably vary a current flow through the transistor pair.

Abstract: In one example, an apparatus comprises a substrate, a first piezoelectric flap, and a second piezoelectric flap. The substrate has an opening. The first piezoelectric flap has a first end on the substrate and has a first portion extending over a first part of the opening, the first piezoelectric flap including first electrodes, in which the first electrodes extend no more than half of a first length of the first portion. The second piezoelectric flap has a second end on the substrate and has a second portion extending over a second part of the opening, the second piezoelectric flap including second electrodes, in which the second electrodes extend no more than half of a second length of the second portion.

Abstract: In some examples, an apparatus comprises a chopper, a first microelectromechanical system (MEMS) device, a second MEMS device, and a processing circuit. The chopper configured is to repeatedly switch states to enable and disable provision of a light signal. The first MEMS device is configured to provide first and second irradiance signals when the chopper is in, respectively, first and second states The second MEMS device is configured to provide first and second reference signals when the chopper is in, respectively, the first and second states. The processing circuit is configured to generate a first signal based on the first irradiance signal and the first reference signal, generate a second signal based on the second irradiance signal and the second reference signal, and provide a third signal at the processing output representing an irradiance measurement of the light source based on a difference between the first and second signals.

Abstract: In one example, an audio device includes a substrate, a first piezoelectric flap, a second piezoelectric flap, a transmit circuit, a first receive circuit, a switch circuit, and a second receive circuit. The substrate has an opening. The first piezoelectric flap has a first end on the substrate and extending over the opening, the first piezoelectric flap having first and second terminals. The second piezoelectric flap has a second end on the substrate and extending over the opening, the second piezoelectric flap spaced from the first piezoelectric flap, the second piezoelectric flap having third and fourth terminals. The transmit circuit has driver outputs. The first receive circuit has first receiver inputs. The switch circuit coupled to the driver outputs and the first receiver inputs, and the first and second terminals. The second receive circuit has second receiver inputs coupled to the third and fourth terminals.

Abstract: An oscillator circuit includes a first BAW oscillator, a first coupling stage, a second BAW oscillator, and a second coupling stage. The first BAW oscillator is configured to generate a first output signal at a frequency. The first coupling stage is coupled to the first BAW oscillator, and is configured to amplify the first output signal. The second BAW oscillator is coupled to the first coupling stage, and is configured to generate a second output signal at the frequency. The second output signal differs in phase from the first output signal. The second coupling stage is coupled to the first BAW oscillator and the second BAW oscillator, and is configured to amplify the second output signal and drive the first BAW oscillator.

Abstract: A micro-mechanical resonator die includes: micro-mechanical resonator die layers; a cavity formed in at least one of the micro-mechanical resonator die layers; and a micro-mechanical resonator suspended in the cavity. The micro-mechanical resonator includes: a base; a first resonator portion extending from the base along a first plane; and a second resonator portion extending from the base along a second plane. The first resonator portion is configured to operate in an out-of-plane flexural mode that displaces at least part of the first resonator portion out of the first plane. The second resonator portion is configured to operate in an out-of-plane flexural mode that displaces at least part of the second resonator portion out of the second plane and out-of-phase relative to the first resonator portion.

Abstract: In some examples, a package comprises a semiconductor die having a first surface and a second surface opposing the first surface, the semiconductor die including circuitry formed in the first surface. The package includes an acoustic waveguide in the semiconductor die, the acoustic waveguide including an array of capacitors. The array of capacitors includes a transducer portion and a diffraction grating portion. The transducer portion is configured to convert signals between electrical signals and acoustic waves, and the diffraction grating portion is configured to direct the acoustic waves toward and receive the acoustic waves from the second surface.

Abstract: A transducer device is described that includes a substrate having an opening, and a cantilever device having a first end on the substrate and a second end suspended over the opening. In at least one example, the cantilever device includes a first piezoelectric layer having a first surface, the first piezoelectric layer having a first poling direction. The cantilever device further includes a second piezoelectric layer having a second surface opposing the first surface, the second piezoelectric layer having a second poling direction, the second poling direction being different from the first poling direction. The cantilever device further includes a first electrode on the first surface, and a second electrode on the second surface.

Abstract: In one example, an apparatus comprises an oscillator having a control input and a clock output. The apparatus also comprises a frequency control circuit having an input and a control output, the control output coupled to the control input, and a reference clock generator having a reference clock output. The apparatus also comprises a multiplexer having a first multiplexer input, a second multiplexer input, a selection input, and a multiplexer output, the first multiplexer input coupled to the clock output, the second multiplexer input coupled to the reference clock output, and the multiplexer output coupled to the input of the frequency control circuit.

Abstract: A tunable bulk acoustic wave (BAW) resonator includes: a first electrode adapted to be coupled to an oscillator circuit; a second electrode adapted to be coupled to the oscillator circuit; and a piezoelectric layer between the first electrode and the second electrode; and a Bragg mirror. The Bragg mirror has: a metal layer; and a dielectric layer between the metal layer and either of the first electrode or the second electrode. The tunable BAW resonator also includes: a radio-frequency (RF) signal source having a first end and a second end, the first end coupled to the first electrode, and the second end coupled to the second electrode; and an amplifier circuit between either the first electrode or the second electrode and the Bragg mirror metal layer.

Abstract: A clock circuit includes a voltage-controlled oscillator (VCO) having a control input and a first clock output. The clock circuit includes a frequency-locked loop (FLL) having an FLL input and a control output, the control output coupled to the control input. A microelectromechanical system (MEMS) resonator-based oscillator has a second clock output. A multiplexer has a first multiplexer input, a second multiplexer input, a selection input, and a multiplexer output. The first multiplexer input is coupled to the first clock output. The second multiplexer input is coupled to the second clock output. The multiplexer output is coupled to the FLL input.

Abstract: An apparatus comprises a piezoelectric resonator, a first active inductor circuit, and a second active inductor circuit. The piezoelectric resonator includes a first resonator terminal and a second resonator terminal. The first active inductor circuit is coupled between the first resonator terminal and a power supply terminal, the first active inductor circuit having a first impedance that reduces with a first frequency where the first frequency is at or above 1 GHz. The second active inductor circuit is coupled between the second resonator terminal and the power supply terminal, the second active inductor circuit having a second impedance that reduces with a second frequency where the second frequency is at or above 1 GHz.

Abstract: A system comprises a digital processing circuit, a frequency modulator, an amplitude modulator, and an adder. The digital processing circuit receives an input signal and a correlation signal and generates a frequency tuning parameter and an amplitude modulation parameter. The frequency modulator generates a frequency modulation signal and the correlation signal. The amplitude modulator receives the amplitude modulation parameter and generates an amplitude modulation signal. The adder receives the frequency tuning parameter and the frequency modulation signal and generates a control signal. In some implementations, the system further comprises a DC feedback circuit that receives the input signal and generates a DC compensation signal. In some implementations, the system further comprises a temperature sensor, a temperature compensation circuit, and a second adder.

Abstract: An oscillator circuit includes a bulk acoustic wave resonator, a differential active inductor circuit, and a gain circuit. The differential active inductor circuit is configured to bias the bulk acoustic wave resonator. The differential active inductor circuit is coupled between the bulk acoustic wave resonator and a power supply terminal. The gain circuit is coupled to the bulk acoustic wave resonator.

Abstract: A clock circuit includes a voltage-controlled oscillator (VCO) having a control input and a first clock output. The clock circuit includes a frequency-locked loop (FLL) having an FLL input and a control output, the control output coupled to the control input. A microelectromechanical system (MEMS) resonator-based oscillator has a second clock output. A multiplexer has a first multiplexer input, a second multiplexer input, a selection input, and a multiplexer output. The first multiplexer input is coupled to the first clock output. The second multiplexer input is coupled to the second clock output. The multiplexer output is coupled to the FLL input.

Abstract: In examples, a semiconductor die comprises a semiconductor substrate having a surface, the surface having first and second surface portions, and a radiator layer on the surface. The radiator layer comprises a metal member having a first metal member portion above the first surface portion and a second metal member portion above the second surface portion, a first distance between the first metal member portion and the first surface portion, and a second distance between the second metal member portion and the second surface portion, the first distance less than the second distance. The radiator layer includes first and second electrodes. The radiator layer includes a piezoelectric layer extending along a length of the radiator layer and on each of the first and second electrodes, the piezoelectric layer between the first and second metal members and the semiconductor substrate.

Abstract: An example apparatus includes: a semiconductor substrate; a mechanical resonator supported by the substrate, the mechanical resonator including an array of capacitors; and a plasmonic infrared (IR) absorber including an array of metal structures. The mechanical resonator is between the substrate and the IR absorber.