Design Of Linear Array Detection And Readout System Applied In Ultraviolet Photon Imaging

The photon detection and counting imaging adopts a detector with single photon detection capability,and the target is scanned and sampled with high precision by means of ultraviolet lenses and scanning table.The photon information is preprocessed and transmitted through the readout circuit.Finally,the imaging processing software is used to obtain the positioning image of the target light source.The photon counting imaging technology has the advantages of high sensitivity,high signal-to-noise ratio and good reliability,and has important engineering application value in the field of weak light detection such as medical detection,camouflage identification,and power grid security monitoring.With the improvement of detector performance and the development of image processing technology,higher and higher requirements are placed on the array scale,detection accuracy and system stability of photon detection systems.Based on the engineering requirements of high-voltage leakage detection,this paper designed a 1×128 linear array detection and readout system for ultraviolet photon imaging,which was realized in combination with the 4HSiC avalanche photo diode(APD)linear array.The detection count for weak light signals.In view of the non-ideal factors such as uniformity deviation and characteristic degradation in large-scale linear array,the circuit design is used to make up for the lack of technology.The readout circuit counts the ultraviolet light source on the basis of adjusting the reverse bias voltage of the detector to improve its uniformity.The built-in APD breakdown protection circuit does not affect the system function when the detector is normal.When a detector unit is damaged by high voltage breakdown due to the characteristic degradation,it can protect the internal circuit from external voltage to a certain extent and shield the high voltage.On this basis,combined with the testability requirements of the circuit,the design of the circuit is completed.According to the scale characteristics of the 1×128 linear array and the requirements of the working environment,the appropriate substrate packaging and PCB mounting method are selected to make the 1×128 linear array photon detection count.The readout circuit has the ability to detect and count ultraviolet light sources.Under the TSMC 0.18?m CMOS process,the Cadence software is used as the platform to complete the circuit simulation optimization,layout design,etc.,and carry out tape test verification.The scale of the photon detection counting readout circuit is 1 × 128,the area of the readout circuit chip is 9945.355?m × 1652.86?m,and the area of a single pixel is 70.5?m × 520?m.The simulation results meet the design requirements.The chip test results show that the function of each module of the readout circuit system is normal,and each pixel circuit can independently perform reverse bias voltage adjustment and photon count transmission.The system frame frequency is adjustable from 1k Hz to 15.6k Hz,the clock frequency is 20 MHz,the dynamic range is 60 d B,and the reverse bias voltage is adjusted in 62.5m V steps from 0 to 2V.The APD breakdown protection circuit can prevent the detector from being damaged to a certain extent,and the external 230 V voltage damages the internal circuit.With the cooperation of an external photon detection platform,the 1 × 128 photon detection counting and reading circuit system can effectively detect the ultraviolet light source,and has the ability to be applied to ultraviolet photon scanning detection imaging.