Research On The Readout Circuit Of 640×480 Pixel Uncooled Infrared Detector

Uncooled infrared detectors have been used in various fields such as security,space science,environmental management,monitoring,etc.With the rapid development of technology,the scale of uncooled infrared area arrays is getting larger and larger,from 128 × 128,320 × 256,to 640 × 480.Larger pixel arrays require higher performance of readout integrated circuits(ROIC)for preprocessing weak photocurrent.The function of the readout circuit is mainly for signal amplification,filtering,sampling,noise reduction and conversion of transmission types.This dissertation studies the readout circuit of 640 × 480 pixel uncooled infrared detector.A new bias circuit is designed to provide bias for the pixels,and the on-chip non-uniformity correction function is added to realize the overall design of the readout circuit.The TSMC 0.18?m process is used to design,simulate,layout and verify the readout circuit.The research contents of this thesis are as follows:1.This paper proposes a new circuit that provides a bias for the detector.By using the deep negative feedback of the operational amplifier to adjust the pixel voltage,a current mirror is used to mirror the current of the blind pixel circuit.In order to reduce the effect of the threshold voltage on the output signal in the conventional bias circuit,the output current of the bias circuit will be affected by many factors because the threshold voltage changes with many factors.The new pixel circuit reduces the influence of the threshold voltage on the pixel circuit,and reduces the current error of the sensitive pixel circuit and the blind pixel circuit.2.In this paper,a non-uniformity correction circuit is added to the bias circuit,and current compensation is performed in a new way with the same resistance value in series but different proportions.The series connection of the resistors uses a 1: 2: 4 mode,which improves the accuracy of compensation for sensitive pixel circuits.Ideally,each cell should respond the same in the same environment.In practice,due to defects in the manufacturing process and other reasons,sensitive pixels will have different response characteristics,which is the direct cause of circuit non-uniformity.After calculation,the non-uniformity of the circuit is less than 3% of the blind pixel resistance.The maximum deviation of the output current value of the pixel circuit is 200 n A.The output current value of the circuit is 210.07 n A by simulation.3.This thesis studies the readout circuit of a small pixel large area array uncooled infrared detector.Including bias circuit,integration circuit,data register circuit,sample and hold circuit,serial to parallel circuit,output buffer circuit.The pixel size is 17?m × 17?m,the size of the array is 640 × 480,and in the TSMC 0.18?m process,the working frame frequency is 60 Hz,the main clock frequency is 19 MHz,the integration capacitor is adjustable,and the readout circuit output swing is 0.8?4.2V.