Abstract: A method includes receiving, by a piezoelectric stack of a transducer, a first piezoelectric voltage. The transducer has a base structure and a first layer, the base structure having a first displacement between a first portion of the base structure and the first layer. The method also includes transmitting, by the transducer, a first ultrasound frequency while receiving a first piezoelectric voltage, and receiving, by the transducer, a first bias voltage. The received first bias voltage alters the first displacement between the first portion of the base structure and the first layer, and the altered first displacement is smaller than the first displacement. The method further includes receiving, by the piezoelectric stack of the transducer, a second piezoelectric voltage to the transducer, and transmitting, by the transducer, a second ultrasound frequency while receiving the first bias voltage and the second piezoelectric voltage.

Abstract: In some examples, a device comprises a ceramic substrate having a cavity, a die pad in the cavity, and a semiconductor die in the cavity and having a first segment coupled to the die pad and a second segment cantilevered over a floor of the cavity. The device also includes a first conductive member in the cavity, the first conductive member coupled to a second conductive member exposed to an exterior of the ceramic substrate. The device also includes a bond wire coupled to a device side of the semiconductor die and to the first conductive member.

Abstract: In one embodiment, a transducer comprises a first piezoelectric stack comprising a piezoelectric material; a first layer in contact with the piezoelectric stack; and a base structure beneath the first layer. The first layer has a first displacement between a first portion of the base structure and the first layer, and the first displacement is configurable by a first bias voltage received by the transducer.

Abstract: An apparatus includes a lens, a transducer and a driver, where the lens has a first side, a second side, and a lens radius, and the transducer has a transducer outer radius. The transducer is coupled to the first side of the lens, and the transducer outer radius is less than the lens radius. The driver has output terminals coupled to the transducer and is configured to provide an oscillating drive signal at a non-zero frequency to vibrate the lens. An o-ring is positioned between a clamp and the second side of the lens, where the o-ring has a nominal radius that is less than or equal to a nominal radius of the transducer.

Abstract: A hybrid micromachined ultrasound transducer includes a piezoelectric micromachined transducer and a capacitive micromachined transducer. The capacitive micromachined transducer is vertically stacked with the piezoelectric micromachined transducer. The piezoelectric micromachined transducer and the capacitive micromachined transducer include a common shared electrode.

Abstract: An example pressure sensor calibration apparatus includes a pressure chamber in which a first pressure sensor is to be disposed; one or more first sensors to determine a capacitance value from the first pressure sensor from a physical test performed on the first pressure sensor; the one or more first sensors to determine a first pull-in voltage value from a first electrical test performed on the first pressure sensor; a correlator to determine correlation coefficient values based on the capacitance value determined during the physical test on the first pressure sensor and the first pull-in voltage value determined during a first electrical test on the first pressure sensor; and a calibrator to determine calibration coefficient values to calibrate a second pressure sensor based on the correlation coefficient values and a second electrical test on the second pressure sensor.

Abstract: In one embodiment, a transducer comprises a first piezoelectric stack comprising a piezoelectric material; a first layer in contact with the piezoelectric stack; and a base structure beneath the first layer. The first layer has a first displacement between a first portion of the base structure and the first layer, and the first displacement is configurable by a first bias voltage received by the transducer.

Abstract: Broadband ultrasound transducers and related methods are disclosed herein. An example ultrasonic transducer disclosed herein includes a substrate and a first membrane supported by the substrate. The first membrane is to exhibit a first frequency response when oscillated. The example ultrasonic transducer includes a second membrane supported by the substrate. The second membrane is to exhibit a second frequency response different from the first frequency response when oscillated. The example ultrasonic transducer includes a third membrane supported by the substrate. The third membrane is to exhibit one of the second frequency response or a third frequency response different from the first frequency response and the second frequency response when oscillated. A shape of the first membrane is to differ from a shape of the second membrane and a shape of the third membrane.

Abstract: An acceleration change sensor includes a flexible member comprising extensions extending from a central portion. Piezoelectric capacitors are provided on respective extensions. A proof mass is coupled to the flexible member and offset from each extension of the plurality of extensions.

Abstract: Methods and apparatus to calibrate micro-electromechanical systems are disclosed. An pressure sensor calibration apparatus includes a pressure chamber in which a first pressure sensor is to be disposed; one or more first sensors to measure a first capacitance value from the first pressure sensor from a physical test performed; the one or more first sensors to measure a second capacitance value from a first electrical test performed on the first pressure sensor; and a correlator to determine correlation coefficient values based on the first capacitance value determined during the physical test on the first pressure sensor and the second capacitance value determined during the first electrical test on the first pressure sensor; and a calibrator to determine calibration coefficient values to calibrate a second pressure sensor based on the correlation coefficient values and a third capacitance value determined during a second electrical test on the second pressure sensor.

Abstract: Methods and apparatus to calibrate micro-electromechanical systems are disclosed. An example pressure sensor calibration apparatus includes a mechanical lift to move a pressure sensor between a first height, a second height, and a third height; one or more sensors to measure first pressure and capacitance values at the first height, second pressure and capacitance values at the second height, and third pressure and capacitance values obtained at the third height; and a calibrator to determine calibration coefficient values to calibrate the pressure sensor based on the first pressure and capacitance values obtained at the first height, the second pressure and capacitance values at the second height, and the third pressure and capacitance values obtained at the third height.

Abstract: In one example, a semiconductor device includes an acoustic medium, a first transducer on the acoustic medium, a first electrode coupled to the first transducer, a second transducer on the acoustic medium, and a second electrode coupled to the second acoustic transducer. The semiconductor device also includes a semiconductor substrate to support the acoustic medium and first and second transducers. Mold compound encapsulates at least a portion of the acoustic medium, the first acoustic transducer, the second acoustic transducer, and the semiconductor substrate.

Abstract: An example pressure sensor calibration apparatus includes a pressure chamber in which a first pressure sensor is to be disposed; one or more first sensors to determine a capacitance value from the first pressure sensor from a physical test performed on the first pressure sensor; the one or more first sensors to determine a first pull-in voltage value from a first electrical test performed on the first pressure sensor; a correlator to determine correlation coefficient values based on the capacitance value determined during the physical test on the first pressure sensor and the first pull-in voltage value determined during a first electrical test on the first pressure sensor; and a calibrator to determine calibration coefficient values to calibrate a second pressure sensor based on the correlation coefficient values and a second electrical test on the second pressure sensor.

Abstract: Methods and apparatus to calibrate micro-electromechanical systems are disclosed. An example pressure sensor calibration apparatus includes a pressure chamber in which a first pressure sensor is to be disposed; one or more first sensors to determine a capacitance value from the first pressure sensor from a physical test performed on the first pressure sensor; the one or more first sensors to determine a first pull-in voltage value from a first electrical test performed on the first pressure sensor; a correlator to determine correlation coefficient values based on the capacitance value determined during the physical test on the first pressure sensor and the first pull-in voltage value determined during a first electrical test on the first pressure sensor; and a calibrator to determine calibration coefficient values to calibrate a second pressure sensor based on the correlation coefficient values and a second electrical test on the second pressure sensor.

Abstract: A hybrid micromachined ultrasound transducer includes a piezoelectric micromachined transducer and a capacitive micromachined transducer. The capacitive micromachined transducer is vertically stacked with the piezoelectric micromachined transducer. The piezoelectric micromachined transducer and the capacitive micromachined transducer include a common shared electrode.

Abstract: Methods and apparatus to calibrate micro-electromechanical systems are disclosed. An pressure sensor calibration apparatus includes a pressure chamber in which a first pressure sensor is to be disposed; one or more first sensors to measure a first capacitance value from the first pressure sensor from a physical test performed; the one or more first sensors to measure a second capacitance value from a first electrical test performed on the first pressure sensor; and a correlator to determine correlation coefficient values based on the first capacitance value determined during the physical test on the first pressure sensor and the second capacitance value determined during the first electrical test on the first pressure sensor; and a calibrator to determine calibration coefficient values to calibrate a second pressure sensor based on the correlation coefficient values and a third capacitance value determined during a second electrical test on the second pressure sensor.

Abstract: Methods and apparatus to calibrate micro-electromechanical systems are disclosed. An example pressure sensor calibration apparatus includes a mechanical lift to move a pressure sensor between a first height, a second height, and a third height; one or more sensors to measure first pressure and capacitance values at the first height, second pressure and capacitance values at the second height, and third pressure and capacitance values obtained at the third height; and a calibrator to determine calibration coefficient values to calibrate the pressure sensor based on the first pressure and capacitance values obtained at the first height, the second pressure and capacitance values at the second height, and the third pressure and capacitance values obtained at the third height.

Abstract: Methods and apparatus to calibrate micro-electromechanical systems are disclosed. An example pressure sensor calibration apparatus includes a pressure chamber in which a first pressure sensor is to be disposed; one or more first sensors to determine a capacitance value from the first pressure sensor from a physical test performed on the first pressure sensor; the one or more first sensors to determine a first pull-in voltage value from a first electrical test performed on the first pressure sensor; a correlator to determine correlation coefficient values based on the capacitance value determined during the physical test on the first pressure sensor and the first pull-in voltage value determined during a first electrical test on the first pressure sensor; and a calibrator to determine calibration coefficient values to calibrate a second pressure sensor based on the correlation coefficient values and a second electrical test on the second pressure sensor.