Design And Reserch On640×512Uncooled Infrared Focal Plane Array Readout Circuit

With the great application of uncooled infrared thermal imaging in all fields, themain pursuit of the current uncooled infrared focal plane array is intelligentsystem-on-chip which has the advantages of larger array, smaller pixels and higherintegrated level with high-performance ability of processing digital signal.In this dissertation, based on the demands of national development, the presentstatus and future trends of the technology of uncooled infrared focal plane array andreadout circuit are introduced. A640×512without Thermo-Electric Cooler(TEC)uncooled infrared focal plane array readout circuit in which the pixel dimensions are25μm×25μm and a14bits single-slope ADC is integrated are proposed. A top-downdesign approach is also used in this dissertation. We firstly make the circuit overallworkflow clear. Then we define the various functional modules and structuralconnections. Finally, we do a detailed circuit design, simulation and analysis of eachmodule. The main contents of this dissertation are summarized as follows:1. According to the actual situation of the readout circuit design and the0.5μmprocess，we design a high-speed640×512infrared focal plane array readout circuit inwhich the frame frequency is30Hz and basic frequency is76.9MHz.2. Based on the main function of the digital control circuit, we finish the detailedcircuits’ design and simulation within the modules of the digital control circuit. Becausethere are many problems existing in the traditional coding/decoding method, forexample, the layout is hard to be realized and the sensor is easy to be chosen for severaltimes, we propose a more reliable shift control method to realize6kinds of row selectedcontrol.3. According to the main function of the analog circuits and design indexes, wefinish the detailed analog circuits’ design and simulation. A new bridge type integralpre-circuit which can make the readout circuit work precisely without TEC is proposed.The temperature coefficient of the output signal is4.11ppm/C@ΔTSub=120K.Simultaneously, a14bits single-slope ADC is integrated in the chip and the ENOB ofthe ADC is13.37bits. 4. The test designs of the readout circuit are presented throughout the readout circuitdesign process. Three kinds of test methods, including digital signal test, high-speeddigital output port and overall function test of the readout circuit, are proposed in thisdissertation, and increase the testability of the readout circuit. Especially, the testmethod for overall function test of the readout circuit solves the problem that the overallfunction test can’t be implemented before the infrared focal plane array is fabricated, sothat the inferiors can be rejected in advanced and the test time and the package cost canbe cut down.