A Design Of Readout Integrated Circuit For Uncooled Vanadium Oxide Infrared Focal Plane Detector

Uncooled vanadium oxide Infrared Focal Plane Array imaging system is widely used in both military and civilian field.It consists of infrared detector and readout circuit,while the latter one is an important part to connect the infrared detector and image signal processing whose performance directly restricts the performance of the entire imaging system.This paper researched the design of readout circuit of uncooled infrared focal plane array.The major works include as follows: 1.It analyzed the operating principle and electrical characteristics of Microbolometer,and fundamental characteristics of Vanadium oxide thermal resistor,summarized the basic structure of the readout circuit,and then analyzed their merits and drawbacks.The capacitor feedback transimpedance amplifier was selected based on the actual requirement.2.It discussed main noise sources of the detector and readout circuit,analyzed their causes and processing methods.3.The design of each core analog digital sub module,the control mode of digital timing and the composition of simulation system were elaborated.4.It used non-uniformity correction that adjust pixel bias voltage to eliminate the inconsistency of output generated by the heterogeneity of process,material and bias.5.Hierarchical processing was used on the output buffer,which could reduce the working speed of the buffer,shorten the stabilization time and reduce the power consumption when compared with adopting only one buffer.6.The redundant structure is designed.It is known to all that the sensor resistance and bias resistance which are reprocessed on a later wafer may be damaged.However,it can be repaired through redundant structures,thereby improving the yield of production.7.The circuit that can counteraction sensors self-heating effect was also designed.The sensor will generate heat when producing current in power.While the sensor itself is a thermistor,the energy generated by its own heat will be counted into the infrared reception of energy so that the output can not fully reflect the real infrared reception of real energy and the deviation occurs.The problem can be solved by compensating the offset circuit in order that the final imaging will be perfect.8.Product level chip design added the clock detection circuit and under voltage protection circuit to reduce the chip failure risk.On this basis,using CSMC(HuaRunshanghua)6S05DPTM technology with massive simulations,in the target of designing simple,practical,stable,low noise,low power CMOS readout circuit structure,conforming to the current mainstream direction of infrared detection technology research,a 384X288 readout circuit is designed.The final performance of the main performance indicators is :NETD:64mK,power:198mW,dynamic range :0.5V~4.5V,frame frequency:60Hz.This paper laid the foundation for the design of more large-scale and higher performance readout circults.