Abstract
This article presents a low-power and small-area transceiver application-specific integrated circuit (ASIC) for 3-D trans-fontanelle ultrasonography. A novel micro-beamforming receiver architecture that employs current-mode summation and boxcar integration is used to realize delay-and-sum on an N-element sub-array using N× fewer capacitive memory elements than conventional micro-beamforming implementations, thus reducing the hardware overhead associated with the memory elements. The boxcar integration also obviates the need for explicit anti-aliasing filtering in the analog front end, thus further reducing die area. These features facilitate the use of micro- beamforming in smaller pitch applications, as demonstrated by a prototype transceiver ASIC employing micro-beamforming on sub-arrays of N = 4 elements, targeting a wearable ultrasound device that monitors brain perfusion in preterm infants via the fontanel. To meet its strict spatial resolution requirements, a 10-MHz 100-µm-pitch piezoelectric transducer array is employed, leading to a per-element die area >2× smaller than prior designs employing micro-beamforming.