Abstract: Aspects of the technology described herein relate to an ultrasound device including a first die that includes an ultrasonic transducer, a first application-specific integrated circuit (ASIC) that is bonded to the first die and includes a pulser, and a second ASIC in communication with the second ASIC that includes integrated digital receive circuitry. In some embodiments, the first ASIC may be bonded to the second ASIC and the second ASIC may include analog processing circuitry and an analog-to-digital converter. In such embodiments, the second ASIC may include a through-silicon via (TSV) facilitating communication between the first ASIC and the second ASIC. In some embodiments, SERDES circuitry facilitates communication between the first ASIC and the second ASIC and the first ASIC includes analog processing circuitry and an analog-to-digital converter. In some embodiments, the technology node of the first ASIC is different from the technology node of the second ASIC.

Abstract: An ultrasound circuit comprising a trans-impedance amplifier (TIA) with built-in time gain compensation functionality is described. The TIA is coupled to an ultrasonic transducer to amplify an electrical signal generated by the ultrasonic transducer in response to receiving an ultrasound signal. The TIA is, in some cases, followed by further analog and digital processing circuitry.

Abstract: An ultrasound circuit comprising a single-ended trans-impedance amplifier (TIA) is described, The TIA is coupled to an ultrasonic transducer to amplify an electrical signal generated by the ultrasonic transducer in response to receiving an ultrasound signal. The TEA is followed by further processing circuitry configured to filter, amplify, and digitize the signal produced by the TIA.

Abstract: A time gain compensation (TGC) circuit for an ultrasound device includes a first amplifier having an integrating capacitor and a control circuit configured to generate a TGC control signal that controls an integration time of the integrating capacitor, thereby controlling a gain of the first amplifier. The integration time is an amount of time an input signal is coupled to the first amplifier before the input signal is isolated from the first amplifier.

Abstract: Circuitry for ultrasound devices is described. A multi-level pulser is described, which can support time-domain and spatial apodization. The multi-level pulser may be controlled through a software-defined waveform generator. In response to the execution of a computer code, the waveform generator may access master segments from a memory, and generate a stream of packets directed to pulsing circuits. The stream of packets may be serialized. A plurality of decoding circuits may modulate the streams of packets to obtain spatial apodization.

Abstract: A variable current trans-impedance amplifier (TIA) for an ultrasound device is described. The TIA may be coupled to an ultrasonic transducer to amplify an output signal of the ultrasonic transducer representing an ultrasound signal received by the ultrasonic transducer. During acquisition of the ultrasound signal by the ultrasonic transducer, one or more current sources in the TIA may be varied.

Abstract: Electrical biasing of ultrasonic transducers of an ultrasound device is described. The ultrasonic transducers may be capacitive micromachined ultrasonic transducers (CMUTs). The ultrasonic transducers may be grouped together, with the different groups receiving different bias voltages. The bias voltages for the various groups of ultrasonic transducers may be selected to account for differences between the groups.

Abstract: An ultrasound device including an asynchronous successive approximation analog-to-digital converter and method are provided. The device includes at least one ultrasonic transducer, a plurality of asynchronous successive-approximation-register (SAR) analog-to-digital converters (ADC) coupled to the at least one ultrasonic transducer, at least one asynchronous SAR in the plurality having a sample and hold stage, a digital-to-analog converter (DAC), a comparator, and control circuitry, wherein a DAC update event following at least one bit conversion is synchronized to a corresponding DAC update event of at least one other ADC in the plurality of ADCs.

Abstract: Methods and apparatus are described for implementing a coding scheme on ultrasound signals received by a plurality of ultrasonic transducers. The coding, and subsequent decoding, may allow for multiple ultrasonic transducers to be operated in a receive mode simultaneously while still differentiating the contribution of the individual ultrasonic transducers. Improved signal characteristics may result, including improved signal-to-noise ratio (SNR).

Abstract: A time gain compensation (TGC) circuit for an ultrasound device includes a first amplifier having an integrating capacitor and a control circuit configured to generate a TGC control signal that controls an integration time of the integrating capacitor, thereby controlling a gain of the first amplifier. The integration time is an amount of time an input signal is coupled to the first amplifier before the input signal is isolated from the first amplifier.

Abstract: Aspects of the technology described herein relate to an apparatus including an ultrasound-on-a-chip device configured to be bound to a user's wrist. The ultrasound-on-a-chip device may include a two-dimensional array of ultrasonic transducers. The transducers may be capacitive micromachined ultrasonic transducers (CMUTs) and may be configured to emit ultrasound waves having a frequency between approximately 5-20 MHz. A coupling strip may be coupled to the ultrasound-on-a-chip device to reduce the air gap between the ultrasound-on-a-chip device and the user's wrist. The ultrasound-on-a-chip device may be waterproof and may be able to perform both transverse and longitudinal ultrasound scanning without being rotated. The ultrasound-on-a-chip device may be configured to calculate pulse wave velocity through a blood vessel in a user's wrist.

Abstract: A variable current trans-impedance amplifier (TIA) for an ultrasound device is described. The TIA may be coupled to an ultrasonic transducer to amplify an output signal of the ultrasonic transducer representing an ultrasound signal received by the ultrasonic transducer. During acquisition of the ultrasound signal by the ultrasonic transducer, one or more current sources in the TIA may be varied.

Abstract: Methods and apparatus are described for implementing a coding scheme on ultrasound signals received by a plurality of ultrasonic transducers. The coding, and subsequent decoding, may allow for multiple ultrasonic transducers to be operated in a receive mode simultaneously while still differentiating the contribution of the individual ultrasonic transducers. Improved signal characteristics may result, including improved signal-to-noise ratio (SNR).

Abstract: Ultrasound devices configured to perform high-intensity focused ultrasound (HIFU) are described. An ultrasound device may include HIFU units configured to emit high acoustic intensities. Multiple ultrasound devices may be disposed on a substrate, which may be configured to be flexed so that the direction of emission of the ultrasound devices can be mechanically controlled. Additionally, or alternatively, the ultrasound beams produced by different ultrasound devices may be electronically oriented by adjusting the phases of the signals with which each element of a device is driven. For example, multiple phased arrays of ultrasound devices may be used to concentrate ultrasound energy into a desired location. In some embodiments, the time at which different ultrasound signals are emitted may be controlled, for example to ensure that the combined signal has at least a desired intensity.

Abstract: Ultrasound devices configured to perform high-intensity focused ultrasound (HIFU) are described. An ultrasound device may include HIFU units configured to emit high acoustic intensities and elasticity detectors configured to determine characteristics of the target area of a human body based on the elasticity of the target area. The elasticity detectors may determine, e.g., whether the target area is healthy, and if not, the type cell in need of treatment (e.g., the type of cancer cell present in the target area). In one example, the elasticity detectors may be configured to determine the stiffness of the target area, which may provide an indication as to the type of cell present in the area, by estimating the velocity of a shear wave propagating away from the target area. The shear wave may arise in response to the application of an ultrasound wave to the target area.

Abstract: Aspects of the technology described herein relate to ultrasound circuits that employ a differential ultrasonic transducer element, such as a differential micromachined ultrasonic transducer (MUT) element. The differential ultrasonic transducer element may be coupled to an integrated circuit that is configured to operate the differential ultrasonic transducer element in one or more modes of operation, such as a differential receive mode, a differential transmit mode, a single-ended receive mode, and a single-ended transmit mode.

Abstract: An ultrasound circuit comprising a single-ended trans-impedance amplifier (TIA) is described. The TIA is coupled to an ultrasonic transducer to amplify an electrical signal generated by the ultrasonic transducer in response to receiving an ultrasound signal. The TIA is followed by further processing circuitry configured to filter, amplify, and digitize the signal produced by the TIA.

Abstract: An ultrasound circuit comprising a trans-impedance amplifier (TIA) with built-in time gain compensation functionality is described. The TIA is coupled to an ultrasonic transducer to amplify an electrical signal generated by the ultrasonic transducer in response to receiving an ultrasound signal. The TIA is, in some cases, followed by further analog and digital processing circuitry.

Abstract: An ultrasound device is describe in which analog ultrasonic transducer output signal are directly converted to digital signals. The ultrasound device includes microfabricated ultrasonic transducers directly coupled to a sigma delta analog-to-digital converter in some instances. The direct digital conversion may allow for omission of undesirable analog processing stages in the ultrasound circuitry chain. In some situations, the ADC may be integrated on the same substrate as the ultrasound transducer.

Abstract: Circuitry for ultrasound devices is described. A multilevel pulser is described, which can provide bipolar pulses of multiple levels. The multilevel pulser includes a pulsing circuit and pulser and feedback circuit. Symmetric switches are also described. The symmetric switches can be positioned as inputs to ultrasound receiving circuitry to block signals from the receiving circuitry.