A 0.91mW/element pitch-matched front-end ASIC with integrated subarray beamforming ADC for miniature 3D ultrasound probes

Data acquisition from 2D transducer arrays is one of the main challenges for the development of emerging miniature 3D ultrasound imaging devices, such as 3D trans-esophageal (TEE) and intra-cardiac echocardiography (ICE) probes (Fig. 10.5.1). The main obstacle lies in the mismatch between the large number of transducer elements (103 to 104) and the limited cable count (<200). Recent advances in transducer-on-CMOS integration have enabled the use of in-probe subarray beamforming based on delay-and-sum (DAS) circuits [1] to reduce the channel count by an order of magnitude. Further reduction calls for in-probe digitization to enable more advanced data processing and compression in the digital domain. However, prior designs [2-4] compromise on transducer pitch (> half wavelength) to accommodate the ADC and consume >9mW/element, which translates into unacceptable self-heating in miniature 3D probes.