与短波和中波器件相比,长波红外探测器具有较大的光电流和暗电流,故需要强大的电荷存储能力.而使用传统的模拟像元读出电路技术会严重受限于电荷存储能力,使得长波探测器的动态范围和信噪比难以提升,从而制约着长波红外成像系统的发展和应用.提出一种像素级数字读出电路技术,通过数字积分克服了传统模拟积分方案电荷存储能力受限的缺陷,实现了探测器的数字信号输出,能够极大提高探测器的动态范围、抗干扰能力和帧频.该技术是提升长波探测器性能的有效途径.基于该技术设计了一款像元间距为30 μm的320×256数字读出电路,其输出以低压差分信号(Low Voltage Differential Sig-nal,LVDS)方式传输.仿真结果显示,该电路的最高帧频可达1000Hz,动态范围大于95 dB.
A Pixel-Level Digital Readout Circuit Design with High Frame Rate and Large Dynamic Range
Compared with short wave and medium wave devices,long wave infrared detectors have larger photocurrent and dark current,so they need strong charge storage capacity.However,the use of traditional analog pixel readout circuit technology is severely limited by charge storage ability,which makes it difficult to improve the dynamic range and signal-to-noise ratio of long-wave detector,restricting the development and ap-plication of long-wave infrared imaging system In this paper,a pixel-level digital readout circuit technology is proposed,which overcomes the limitation of charge storage capacity of traditional analog integration scheme.The digital signal output of detector is realized.The dynamic range,anti-interference ability and frame rate of detector improve greatly.This technique is an effective way to improve the performance of long wave detector.Based on this technology,a digital readout circuit with 320X256 array and pixel spacing of 30 μm is designed.The output is transmitted by LVDS.The simulation results show that the maximum frame rate of the circuit can reach 1000 Hz,and the dynamic range is greater than 95 dB.
readout circuitpixel-leveldigitalhigh frame ratehigh dynamic range
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