Research On Low Power High Sensitivity Photodetection Integrated Circuit And System

CMOS photodetection biosensor which is based on large scale integrated circuit (VLSI) technology has been widely used in environmental monitoring, medical electronics, life science and other applications. Photodetection is a developing hot spot of microelectronic technology in recent years. In this thesis, the analysis of two applications of photodetection sensor is presented including organophosphorus detection which is applied in the field of environmental monitoring and macromolecules detection which is applied in life science. The high sensitivity, low noise and low power consumption of the photodetection sensor is focused.Aimed at the application requirement of hand-held organophosphorus compounds detection which includes low speed, high precision, low power consumption, this thesis makes a detail analysis of photodetection system including the system architecture, photodetection sensor front end, key module circuit. To achieve high sensitivity, high input dynamic range in low power consumption, the folded-reference voltage pulse-width modulating is proposed in this thesis. A photo to pulse width detection circuit is accomplished in this thesis which is implemented in 0.18um CMOS process. The sensitivity of the photodetection sensor is 3.6nW/cm2 and the dynamic range is 71dB. The sensor is supplied in 1.8V and the power consumption is 14.5uW. Based on this photodetection sensor, the design of handheld systems detecting organophosphorus is accomplished. The limit of detection (LOD), one of the most important performance indexes, is 0.4uM which can comparable with commercial apparatus. According to the application characteristics, broadband amplification and DC suppression, of macromolecules detection, this thesis presents a detail analysis of the circuit structure, focusing on using low pass filter network feedback to suppress the DC component of input signal and amplify AC signal. The DC suppression photocurrent readout circuit is verified in printed circuit board. Test results shows that the transimpedance gain is 1.5M ohms. The bandpass frequency is 400Hz-50kHz. The maximum DC suppression signal of input signal is 4uA.