CMOS APS用移位寄存器抗SEU加固方法

电离辐射环境中使用的CMOS 有源像素图像传感器(APS)的基于反相器的准静态移位寄存器容易发生单粒子翻转(SEU)，而致使CMOS APS不能正常工作。本文对基于反相器的准静态移位寄存器中的单粒子翻转效应进行了分析，其对单粒子瞬态(SET)最敏感的节点存在于反相器的输入端，反相器的输入阈值电压和输入节点电容决定了其抗SEU的能力。提出了用施密特触发器代替反相器的加固方案，因施密特触发器的电压传输特性存在一滞回区间，所以有更高的翻转阈值，从而可获得更好的抗SEU能力。仿真结果表明，采用施密特触发器的移位寄存器结构较原电路结构的抗SEU能力提高了约10倍。

SEU-Hardened Design for Shift Register in CMOS APS

The inverter-based quasi-static shift register in CMOS APS, which is used in ionizing radiation environment, is susceptible to single event upset (SEU), thus affecting the CMOS active pixel sensor (APS) working. The analysis of the SEU for inverter-based quasi-static shift register concludes that the most sensitive node to single event transient (SET) exists in the input of inverter, and the threshold voltage and capacitance of input node of inverter determine the capability of anti-SEU. A new method was proposed, which replaced the inverter with Schmitt trigger in shift register. Because there is a hysteresis on voltage transfer characteristic of Schmitt trigger,there is high flip threshold, thus better capability of anti-SEU can be achieved. Simulation results show that the anti-SEU capability of Schmitt trigger is 10 times more than that of inverter.