Abstract-This paper demonstrates a four-channel transceiver chip for medical ultrasonic imaging, interfacing to the capacitive micromachined ultrasonic transducers (CMUTs). The high-voltage transmitter (Tx) uses a three-level pulse-shaping technique with charge recycling to improve the power ef¿ciency. The design requires minimum off-chip components and is scalable for more channels. The receiver is implemented with a transimpedance ampli¿er (TIA) topology and is optimized for tradeoffs between noise, bandwidth, and power dissipation. The test chip is characterized with both acoustic and electrical measurements. Comparing the three-level pulser against traditional two-level pulsers, the measured Tx ef¿ciency shows 56%, 50%, and 43% more acoustic power delivery with the same total power dissipation at 2.5, 3.3, and 5.0 MHz, respectively. The CMUT receiver achieves the lowest noise ef¿ciency factor compared with that of the literature (2.1 compared to a previously reported lowest of 3.6, in units of mPA ). In addition, the transceiver chip is tested as a complete system for medical ultrasound imaging applications, in experiments including Tx beamformation, pulse-echo channel response characterization, and ultrasonic Doppler Àow rate detection.Index Terms-Capacitive micromachined ultrasonic transducer (CMUT), charge recycling, multilevel pulse shaping, noise ef¿ciency factor (NEF), pulse-echo response, transimpedance ampli¿er (TIA), transmitter (Tx) ef¿ciency, Tx beamformation, ultrasonic Doppler Àow rate detection, ultrasonic transceiver.

Over the past half-century, ultrasound imaging has become a key technology for assessing an ever-widening range of medical conditions at all stages of life. Despite ultrasound’s proven value, expensive systems that require domain expertise in image acquisition and interpretation have limited its broad adoption. The proliferation of portable and low-cost ultrasound imaging can improve global health and also enable broad clinical and academic studies with great impact on the fields of medicine. Here, we describe the design of a complete ultrasound-on-chip, the first to be cleared by the Food and Drug Administration for 13 indications, comprising a two-dimensional array of silicon-based microelectromechanical systems (MEMS) ultrasonic sensors directly integrated into complementary metal–oxide–semiconductor-based control and processing electronics to enable an inexpensive whole-body imaging probe. The fabrication and design of the transducer array with on-chip analog and digital circuits, having an operating power consumption of 3 W or less, are described, in which approximately 9,000 seven-level feedback-based pulsers are individually addressable to each MEMS element and more than 11,000 amplifiers, more than 1,100 analog-to-digital converters, and more than 1 trillion operations per second are implemented. We quantify the measured performance and the ability to image areas of the body that traditionally takes three separate probes. Additionally, two applications of this platform are described—augmented reality assistance that guides the user in the acquisition of diagnostic-quality images of the heart and algorithms that automate the measurement of cardiac ejection fraction, an indicator of heart health.

No abstract

No abstract

No abstract