A readout integrated circuit for sensitive infrared photodetection operating in intense backgrounds

Abstract

Infrared photodetection generally presents some u.ndesirable features: low detector shunt resistance, large pixel dark current, high noise levels, and intense background signal. These impose challenges to design the readout integrated electronics to properly extract signal information from the detector, mainly due to the effect of low injection efficiency and the limited on-chip voltage supply. Signal sensitivity and saturation are, therefore, often compromised. This work presents the analysis of a readout integrated circuit, coined as the Bouncing Pixel, that prevents signal saturation and that is suitable for infrared electronics due to its high injection efficiency, high sensitivity of 51.65 mV/μA and high dynamic range of at least 105 dB. The simulation data presented in this work follows an application driven design flow for a CO2 gas detection system, considering real models for the infrared light source and the photodetector, optical modeling using the HITRAN database, and reliable readout integrated circuit simulation using device models for a standard TSMC CMOS 180 nm technology. Circuit noise analysis is included. Simulations show that the detection of a CO2 molar fraction as low as 3 ppm could be achieved, suggesting that the Bouncing Pixel is a good solution for high performance infrared readout integrated electronics, even with low chip supply voltages.