Research On Key Technologies Of Pixel Level Digitization For Infrared Readout Integrated Circuit

With the continuous development of infrared detection technology,there is a development trend of large area array and high performance in the domain of infrared readout integrated circuit,while the previous column-level digitization method has gradually exposed its inherent disadvantages of limited frame frequency and high transmission path noise,which cannot meet the requirements of development trends.The pixel-level digitization method has the advantages that the frame rate is independent of the size of the area array,and has strong anti-interference,which has become one of the key directions of domestic and foreign research.Therefore,it is necessary to study pixel-level digitization to improve the performance of infrared readout circuits.First of all,combined with the design indicators,using the Multi-Channel Bit-Serial(MCBS)analog-to-digital conversion mechanism,the overall pixel-level digital readout circuit with an array size of 640×512 and an output frame frequency of 100 Hz is designed.The process of analog-to-digital conversion and data output adopts the pipeline work strategy,which determines the work flow of the readout circuit and the cycle requirements of each step.Aiming at the problem of limited available area for pixel-level digitization,on the basis of Multi-Channel Bit-Serial method,a 2×2 pixel sharing circuit structure is used.The key modules in the pixel sharing circuit including integrating circuit,comparator and latch are designed,and finally the pixel circuit simulation is carried out.The results show that the linearity of the integral output voltage reaches 99.9%,the resolution accuracy of the comparator reaches 14 bits,and the input voltage of 122?V can be resolved.The conversion linearity of the designed pixel-level circuit reaches 99.9%finally.Aiming at the problem of increasing the complexity of digital control circuits brought about by pixel-level digitization,based on the semi-custom design process,the front-end modeling of the digital control circuit is carried out using hardware description language.In addition to completing the basic functions of providing sequential control signals and data transfer output,extra functions such as programmable windowing,optional resolution,and adjustable analog-to-digital conversion bits(7?14 bits)are designed.Physical realization of the circuit are completed through synthesis and placement and routing.The results show that the functions of digital control circuit are normal,the power consumption is about 51.23 m W,and the area is about 2.52 mm~2.Through the research on the above problems,the design and simulation of the key circuit in pixel are completed,and the front-end model and the back-end physical realization of the digital control circuit are carried out.It provides a certain technical basis for pixel-level digitization,especially the pixel-level digitization of infrared readout circuit based on MCBS analog-to-digital conversion.