A 1.5-mm diameter single-chip CMOS front-end system with transmit-receive capability for CMUT-on-CMOS forward-looking IVUS

Integration of receive and transmit electronics and transducer array elements on a single chip is critical for successful implementation of a highly-flexible forward-looking (FL) IVUS imaging catheter. Single-chip integration reduces the interconnect complexity significantly, and enables the ultimate miniaturization of IVUS arrays. Here we describe a single-chip FL-IVUS system based on a front-end IC implemented in 0.35-μm CMOS that is integrated with a 1.4-mm diameter CMUT array using CMUT-on-CMOS technology. The IC incorporates a pulser capable of generating 25-V pulses and a low-noise receiver transimpedance amplifier dedicated to each of the 56 Tx and 48 Rx CMUT array elements, respectively. The chip also includes a digital control circuitry that is designed to synchronize transmitting and receiving sequence during the data acquisition. All of the active circuitry fits into a size of 1.5-mm diameter silicon donut shape with a 430-μm gap left inside for a guide wire. The single-chip FL-IVUS system requires only 13 external connections and provides 4 parallel outputs. The average power consumption of the chip is reduced to 20 mW by biasing off the unused receive amplifiers using the digital logic. Characterization results of the low-noise preamplifiers in the IC after monolithic integration with the FL-IVUS CMUT array are presented. Successful implementation of the single-chip FL-IVUS system is also demonstrated through a volumetric imaging experiment.