A 1-Transistor SPAD Quanta Image Sensor for High-Speed and Small-Pitch Arrays

A SPAD-based pixel with a single transistor has been designed and implemented in a 150nm standard CMOS technology for the realization of a Quanta Image Sensor (QIS). The inherently digital nature of the SPAD device minimizes circuitry and simplifies the achievement of singlephotoelectron sensitivity. The pixel revamps the concept of CMOS passive-pixel sensors to achieve a pixel with a pitch of 7μm and a geometrical fill-factor of 31% in an unoptimized process. The speed of the presented QIS architecture is limited only by the output interface, while requiring extremely simple column circuitry such as a sense amplifier, thus minimizing power requirements.