Development of a low-noise analog front-end ASIC for APD-PET detectors

We report on the development of a front-end ASIC for high spatial resolution PET detectors with time-of-flight capability based on LYSO scintillator arrays coupled with position-sensitive avalanche photodiode (APD) arrays. The ASIC is designed based on the open-IP LSI project led by JAXA and realized in TSMC 0.35-μm CMOS technology. It consists of an 8-channel charge-sensitive amplifier, band-pass filters, differentiators, pulse-height and timing discriminators, and two-channel time-to-amplitude converters. As a result, energy resolution of 9.7% (FWHM) is obtained at 511 keV, with a time resolution below 970 ps (σ). We will also report on the current status of developing a second-version ASIC designed to have 32-channel analog circuits with improved time resolution.