A novel Gate-Controlled Lateral Thyristor based Pixel for Low-Light Image Sensors

CMOS low light level image sensor is popular research in international imaging devices. Thyristors biased at the switching point have significant amplification factors owing to internal cross-coupled bipolar transistors. However, it is tough to operate thyristors quickly at the switching point to achieve low light detection because of the inherently unstable characteristics. This paper proposes a novel gate-controlled lateral thyristor (GC-LT), which can be operated in the transition region and have a high sensitivity performance in low light. Simulation results show that the trigger time of the photodetector is sensitive to the light intensity ranging from 1×10
^-9
to 2.5×10
^-6
W/cm
²
. A sampling circuit and a slope following operation scheme are proposed to record and quantify the light-sensitive trigger time. The pixel size of 15×15 μm
²
is designed and simulated using a 0.6-µm 2-poly 3-metal SOI-CMOS process.