Intracardiac echocardiography (ICE) is an ultrasound sonogram that visualizes the anatomical structure of the heart in real time, with a mm-scale catheter inserted through the intracardiac vessels, and guides surgical intervention for atrial septal defect (ASD) closure. To achieve high-quality medical imaging, an ICE system must meet stringent power consumption requirements with low-noise operation. Since an ASIC and ultrasound transducers are tightly bonded through flip-chip or direct integration, an ultrasound unit TRX channel must be pitchmatched to each transducer channel [1,2]. A piezoelectric Micromachined Ultrasound Transducer (pMUT) is a suitable ultrasound transducer for implantable sensor applications, since it does not need high (~200V) bias that is a must in capacitive MUTs (cMUT) [3]. However, pMUT devices suffer from process variation, which leads to low image quality, and to date, no work addresses this issue for both TX/RX in real time. To meet all these requirements at once, we present a 6×6 TRX pitch-matched pMUT ASIC with a standard CMOS-compatible 13.2V HV pulser, on-chip per-pixel calibration scheme, and a Dynamic Bit-Shared (DBS) ADC for portable ICE applications. 

  - Charge Recycling High Voltage TX 

  - Dynamic Bit Shared SAR ADC 

  - Attenuation-Adaptive AFE 

  - ISSCC 2019 [pdf]