A mini-SiPM array for PET detectors implemented in 0.35-µm HV CMOS technology

A new architecture for Positron Emission Tomography visible-light detectors is presented. The architecture is based on mini-SiPMs (arrays of 32 SPADs), which are locally digitized. With this architecture we expect to achieve a high fill factor while still performing an early enough analog-to-digital conversion so as to avoid interconnect parasitics common of standard SiPMs. The detector is implemented as a 14 × 10 pixel array where each pixel contains a mini-SiPM, a digital counter and individual SPAD SRAMs for disabling high DCR devices. The achieved fill factor is 29% and the expected maximum event rate is 16 kcps.