Design And Analysis Of Signal Readout Circuit For Uncooled Infrared Focal Plane Array

Infrared Thermal imaging technology is an important part of night vision technology.By virtue of its small size,light weight and easy portability,uncooled Infrared Imager has become the focus of the development of infrared thermal imaging technology nowadays.With the booming of internet of things and computer vision,uncooled infrared imaging technology will assume more target detection function.Uncooled infrared focal plane array and readout integrated circuit are the core components of Uncooled Infrared Imager,in which the readout circuit mainly completes the transformation,amplification,sampling and output of the electrical characteristics of the focal plane pixels.According to the principle of uncooled infrared thermography,this paper first introduces the theory of infrared thermal imaging,which provides a theoretical basis for the design and analysis of readout circuits.The readout circuit presented in this paper consists of bias circuit module,CTIA integral amplification module,sampling and holding module and timing control module.After comparing two kinds of bias modes of voltage bias and current bias,this paper chooses a more linear range of current bias as the bias circuit of readout circuit.In this paper,the advantages and disadvantages of 5 kinds of integrated amplifier circuits and their application range are analyzed,and the capacitance feedback impedance amplifier(CTIA)is selected as the integral amplification module of readout circuit.In order to restrain the low-frequency noise contained in the readout circuit output signal,a sampling and holding circuit based on the correlated double sampling strategy is used.Finally,the feasibility of the readout circuit is verified by simulation.In this paper,the noise of the readout circuit is analyzed.The system performance is analyzed by changing the offset current size and the integration time length.It provides a theoretical basis for the selection of circuit-related parameters in practical engineering,and chooses reasonable circuit parameters according to the frame rate,output intensity and temperature resolution of the actual system.In this paper,the nonuniformity of the image element response of uncooled infrared focal Plane array is analyzed,two kinds of common correcting methods are introduced,and the Nonuniformity correction method of non refrigeration focal plane based on bias current is proposed,which corrects the difference between the initial resistance and the absorption efficiency of the pixels.The calibration method is verified by simulation.