LUCAS: A CMOS-Based Fast Readout ASIC for Silicon Photomultipliers -- Measurement and Performance Evaluation

Abstract

This paper presents the design, implementation, and performance evaluation of LUCAS, a low-power, ultra-low jitter ASIC optimized for SiPM readout in Time-of-Flight Computed Tomography (ToF-CT) applications. Leveraging a novel preamplifier design with low input impedance and current-mode operation, LUCAS addresses challenges such as parasitic capacitance of SiPMs and high-speed detection requirements. The ASIC, fabricated in TSMC 65nm CMOS technology, features eight channels with an integrated preamplifier and comparator, achieving an SPTR of 201 ps FWHM at 3.2 mW/ch. Experimental validation includes input impedance measurements, SPTR testing with a pulsed laser source, and energy-to-Time-over-Threshold calibration using monoenergetic X-ray sources. The results demonstrate the effectiveness of LUCAS in enhancing timing resolution while minimizing power consumption, offering significant advancements for high-resolution ToF-CT imaging.