Design Of Digital Control Circuit For Large Scale Uncooled Infrared Focal Plane Array Readout Integrate Circuit

Infrared is a kind of invisible light with thermal effect whose wavelength is between 760 nm and 1mm,and it can be generated by all the objects whose temperature are higher than absolute zero.The uncooled infrared detector based on microbolometer is just a temperature detector based on this principle.Uncooled infrared detector has been widely studied and applied in the national economy because of its advantages such as no refrigeration,small weight and volume,low power consumption and so on.As a key component that affects the performance of detector,ROIC(Read out integrated circuit)is also one of the focuses in the field of modern infrared technology.In order to adapt to the development of the third-generation intelligent smart infrared detector,the uncooled infrared detector readout circuit is developing in the direction of large array,high speed,high integration and digitization,and the digital control circuit in readout circuit is the key to achieve these requirements.Digital control circuit of uncooled infrared focal plane array readout circuit of microbolometer type is studied in this paper.The main research contents and achievements are summarized as follows:(1)The design specifications of large scale uncooled IRFPA readout circuit is proposed,including 1280 × 1024 array size,60 Hz output frame rate,14 bit output precision per pixel,chip area ? 20 mm × 20 mm,power consumption ? 300 mW.According to the design specifications,the difficulties in the design process are analyzed,and a semi customized design method is proposed to shorten the design cycle.At the same time,a scheme of integrating the column level nonuniformity correction module in the readout circuit is proposed,which effectively reduces the power consumption,cost and complexity of the infrared focal plane detector.(2)The important parameters of the digital control circuit of the readout circuit are designed according to the requirements of the design index,such as the clock frequency,the number of output channels and so on.The design is divided into five modules according to the function,including signal input module,timing control module,on-chip offset correction module,array selection module and signal output module.At the same time,a new window function implementation method and a pixel protection scheme are proposed in the module design.The former effectively improves the image output frame rate of window mode,and the latter protects the pixels from overheating or even burning when the readout circuit fails.(3)The design and result analysis of the digital control circuit of the readout circuit are realized according to the semi customized process,the design process includes modeling the digital control circuit by the use of HDL,establishing a test environment for the logical simulation,logic synthesis,physical design to generate layout file,etc.The analysis of the design results shows that the area of the digital control circuit is 3.463 mm2 and the power consumption is 242.4 mW,which fully meets the design requirements.Based on the above research and implementation process of the digital control circuit of the readout circuit,the design of the digital control circuit with reliable performance,more perfect functions and shorter design cycle is realized.