Fully Integrated Pitch-Matched AlScN PMUT-on-CMOS Array for High- Resolution Ultrasound Images

This paper presents a fully integrated pitch-matched PMUTs-on-CMOS array with high potential in catheter-based ultrasound imaging systems and capabilities to obtain resolutions under 100 μm. The system-on-chip consists of 7x7 AlScN PMUTs connected in a 1-D configuration where the six external rows are used to generate the acoustic pressure through three HV-pulser CMOS circuits, and the central row is used to sense the incoming ultrasound wave which will be amplified by a LNA CMOS amplifier. The experimental verification in a liquid environment gave, as a first result, a peak frequency of 7.7 MHz with a normalized pressure (ST) of 1.98 kPa _pp *mm*V ^-1 and receiving sensitivity (SR) of 3.3 V/MPa, respectively, competitive sensitivities in comparison with the state-of-the-art. In the second part, ultrasonic imaging for different wires with a minimum diameter of 25 μm was demonstrated as expected from numerical simulations. The system's performance for ultrasound images was evaluated considering the product of the area and the resolution at 1 mm, giving competitive values compared to other reported ultrasound systems for catheter-based medical ultrasound imaging and the only one providing monolithically integration with the CMOS front-end circuitry.