消除CDS折叠效应的增益自适应红外焦平面读出电路  

Adaptive-gain infrared focal plane array readout circuit with anti-fold CDS

作　　者：吴双 张健怡 陈洪雷[1] 丁瑞军[1] Wu Shuang;Zhang Jianyi;Chen Honglei;Ding Ruijun(Key Laboratory of Infrared Imaging Materials and Detectors,Shanghai Institute of Technical Physics,Chinese Academy of Sciences,Shanghai 200083,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院上海技术物理研究所中国科学院红外成像材料与器件重点实验室,上海200083 [2]中国科学院大学,北京100049

出　　处：《红外与激光工程》2024年第5期83-94,共12页Infrared and Laser Engineering

摘　　要：高动态范围是红外焦平面探测技术的先进发展方向之一。高集成度像元读出电路的动态范围受到小电荷存储容量和噪声的限制。所设计的增益自适应像元读出电路,小信号下为电容反馈跨阻放大器(CTIA),大信号下自动转换为变阻抗电阻反馈跨阻放大器(RTIA),实现小信号大增益、大信号小增益的自动切换,将集成3.86 fF积分电容的CTIA电荷容量拓展到1.63 Me^(–)。在15μm像元中心距的像元内集成相关双采样(CDS)结构,大幅减小噪声。对CDS大信号注入产生的折叠效应进行理论分析,并设计抗折叠结构。采用180 nm 3.3V CMOS工艺,完成640×512规模的读出电路的设计、仿真、流片、测试。测试结果显示,该电路可消除CDS折叠效应,噪声电子数17 e^(–),动态范围拓展到99.66 dB。Objective High dynamic range(HDR)is an important requirement of the advanced Infrared Focal Plane Array(IRFPA).It is limited by the small electric charge capacity and noise of readout integrated circuit(ROIC).One of the common strategies to expand electric charge capacity is well capacity adjusting based on selectable integration capacitors.The other method is multiple sampling implemented by analog-digital converter(ADC)in conjunction with time delay and integration(TDI)technique.However,capacitors and ADC occupies large area,and TDI causes low frame frequency.Correlated double sampling(CDS)is commonly used to reduce low-frequency noise and KTC noise.Nevertheless,the fold effect of CDS due to large-signal saturation,which leads to wrong readout of large-signal,lacks analysis and elimination.Therefore,it is necessary to propose a new structure to enhance the charge capacity in small pixel area and incorporate CDS guaranteed large-signal readout.For this purpose,an adaptive-gain ROIC(AGROIC)integrated with anti-fold CDS(AFCDS)is designed in this paper.Methods The AGROIC and AFCDS is constructed in this paper.AGROIC is accomplished by CTIA in parallel with a MOSFET M_(ag)whose gate voltage is adjustable(Fig.2).The small-signal is integrated through a large-gain CTIA with small capacitor,while the large-signal is injected through the MOSFET,which convert CTIA to RTIA.The conversion gain of ROIC is transformed from the ratio of time to integral capacitance to the reciprocal of the transconductance(Fig.3).The CDS fold effect is caused by saturation of input signal(Fig.7).A fully-passive CDS connected with a MOSFET switch M_(af)is combined with AGROIC to suppress noise of small-signal(Fig.8).In contrast,the switch turns on in response to large-signal resulting in direct injection to the sampling capacitance(Fig.9).Results and Discussions The proposed AGROIC and AFCDS are integrated in 15μm pixel pitch,designed in 180 nm 3.3 V CMOS process.The simulation results demonstrate the aforementioned analysis(Fig.4,Fig.11).A 6

关 键 词：红外焦平面读出电路 增益自适应 抗折叠CDS CTIA 高动态范围 低噪声 

分 类 号：TN215[电子电信—物理电子学]