CMOS single photon sensor with in-pixel TDC for Time-of-Flight applications

A CMOS imager that combines single photon sensitivity with photon timing capabilities has been developed for Time-Of-Flight (TOF) measurements and for Time-Correlated Single-Photon Counting (TCSPC) applications. A test structure with 32×4 pixels is presented in this paper. Each pixel is based on a 30 μm diameter Single-Photon Avalanche Diode (SPAD) with low Dark Counting Rate (60 cps at room temperature) and a Time-to-Digital Converter (TDC) with 400 ps resolution. Some preliminary measurements confirm the possibility to use this SPAD array in a 3D TOF scanning system.