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 apparatus comprising: a microelectromechanical system (MEMS) resonator; and a metal stack over the MEMS resonator, the metal stack including a first metal layer, a second metal layer, and first and second metal vias coupled between the first and second metal layers, at least one of the first or second metal layers overlapping at least part of the MEMS resonator. some of the ferroelectric capacitors.

Abstract: An apparatus is described which comprises a substrate having a through opening and a membrane over the through opening. In at least one example, the apparatus comprises a first beam coupled between a first side of the membrane and the substrate, the first beam including a first stress sensor. In at least one example, the apparatus further comprises a second beam coupled between a second side of the membrane and the substrate, the second side opposing the first side, and the second beam including a second stress sensor.

Abstract: An apparatus includes a die, a bonding layer, and a film. The die includes a semiconductor substrate, a metallization structure on the semiconductor substrate, and a dielectric material around at least a part of the metallization structure. The bonding layer is on the metallization structure. The film is attached on the bonding layer. The film includes a piezoelectric material.

Abstract: A microelectromechanical systems (MEMS) resonator includes a substrate, an array of ferroelectric capacitors on the substrate, and a three-dimensional metal stack above the array of ferroelectric capacitors. The three-dimensional metal stack may include more than two metal layers. Each of the metal layers is coupled to another of the metal layers by more than two metal vias.

Abstract: A motion sensor is described including a semiconductor substrate including a cavity; a mass portion over a bottom of the cavity; a beam coupled between the mass portion and a side of the cavity; and a pair of sensing elements at a distal end of the beam away from the mass portion and being part of the beam or on two opposing sides of the beam. The motion sensor further includes a processing circuit coupled to the pair of sensing elements and configured to receive first signals from the pair of sensing elements and provide a second signal representing a measurement of a motion of the motion sensor based on the first signals.

Abstract: An apparatus is described which comprises a substrate including a cavity and first and second anchors. In at least one example, the apparatus comprises a cantilever including a first portion, a second portion, and a third portion, the first portion coupled between the second and third portions, the first portion coupled to the first and second anchors and is suspended over the cavity, and a length of the first portion along a dimension is shorter than respective lengths of the second and third portions along the dimension.

Abstract: A transducer device is described which comprises a substrate having an opening through the substrate. The transducer device further comprises a first tapered cantilever having a first edge and a second edge, wherein the first edge is opposite to the second edge, wherein the first edge is on the substrate, wherein at least part of the second edge is suspended over the opening, the second edge being longer than the first edge. The transducer device further comprises a second tapered cantilever having a third edge and a fourth edge, wherein the third edge is opposite to the fourth edge, wherein the third edge is on the substrate, wherein at least part of the fourth edge is suspended over the opening, the fourth edge being longer than the third edge.

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: 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 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 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: 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: 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 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 microelectromechanical systems (MEMS) resonator includes a substrate, an array of ferroelectric capacitors on the substrate, and a three-dimensional metal stack above the array of ferroelectric capacitors. The three-dimensional metal stack may include more than two metal layers. Each of the metal layers is coupled to another of the metal layers by more than two metal vias.