Design Of Wide Dynamic Range Readout Circuit For Ultraviolet Detection System

Ultraviolet detection system has the advantages of concentrated spectral response and low noise,and has attracted much attention in military and civil fields.As an important part of the UV detection system,the read-out Integrated Circuit(ROIC)mainly completes the functions of bias setting,signal conversion,sampling and output of the detector.As the main trends of readout circuits,the high sensitivity,wide dynamic range and low noise are the mainstream development directions in the future.In this paper,based on the practical application requirements,according to the equivalent circuit model of a new type of zinc oxide(Zn O)UV detector,a ROIC with high linearity,large output swing and wide dynamic range is designed.The gain can be automatically adjusted under the action of the gear control circuit by using the four-speed gain switching strategy.The complex input stage is composed of a Capacitive Transimpedance Amplifier(CTIA)circuit and an improved gate modulated current mirror circuit.The CTIA structure contains two feedback capacitors,which is used for small current detection.It has the characteristics of high injection efficiency and stable bias voltage.At the same time,in order to improve the ability of detecting small current,a time-sharing method of integrating capacitor and band-limiting capacitor is proposed,which effectively improves the output SNR.The improved gate modulated current mirror circuit is used for high current detection,which is shared by the op amplifier and CTIA.At the same time,this paper analyzes the working mode and timing control of the readout circuit,and puts forward the working mode of first reset and then switch,which effectively improves the detection accuracy.Based on the CMOS process of TSMC 0.35?m,the circuit and layout design of a wide dynamic range ROIC system with array size of 2×2 were completed on Cadence.The chip test results show that the system function is normal,the integral/response period is 1ms at room temperature and 5V supply voltage,the linearity of each segment is above 97%,the minimum linear output swing is 2.95 V,and the chip average current power consumption is 3.481 m A.However,due to the limitation of test conditions,the influence of noise and parasitic parameters,the noise performance of the circuit is obviously attenuated compared with the simulation results.The dynamic range is 146.02 d B,and the effective current detection range is from 50 p A to 1m A,which has a certain gap with the simulation results.Finally,some feasible suggestions are putted forward for the design improvement of subsequent circuits.