11.1 A 5.37mW/Channel Pitch-Matched Ultrasound ASIC with Dynamic-Bit-Shared SAR ADC and 13.2V Charge-Recycling TX in Standard CMOS for Intracardiac Echocardiography

Abstract

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 pitch-matched to each transducer channel [1], [2]. A piezoelectric Micro-machined Ultrasound Transducer (pMUT) is a suitable ultrasound transducer for implantable sensor applications, since it does not need high $(\sim 200\mathrm {V})$ 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 $6 \times 6$ 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.