SRAM单粒子锁定效应电路级防护设计研究

Research on Circuit Level Protection Design of SRAM Single Event Latch-up Effect

高密度CMOS工艺SRAM对单粒子锁定极端敏感的特性使其在空间应用时必须采取相应的防护策略。对于抗辐照能力较弱的CTOS,电路级防护成为提高系统可靠性的一项重要内容。利用激光单粒子效应试验装置,对CYPRESS公司的CY62167DV30LL型SRAM开展了一系列单粒子锁定效应试验。通过对试验结果进行线性拟合,计算出该款SRAM维持电压为1.5~1.6 V,维持电流为9.9~11.2 mA。根据维持电流、维持电压、工作电流、工作电压,对能否采用电路级防护做出判断。提出了电源限流和分压电阻两种电路级防护方法,并定量计算出电源限流取值和分压电阻取值范围。以往文献中电阻只是作为锁定被触发后限流的一种手段,并不能阻止器件发生锁定,本研究发现在满足一定条件下分压电阻可达到退出锁定的目的。两种防护方法均通过脉冲激光试验进行了验证。

SRAM with high density CMOS technology is extremely sensitive to single event latch-up,so it is necessary to adopt corresponding protection strategies in space applications.For CTOS with reduced radiation resistance,circuit level protection becomes an important part to improve system reliability.A series of single event latch-up effect tests were carried out on CY62167 DV30 LL SRAM of CYPRESS Company by using laser single event effect test device.Through the linear fitting of the experimental results,the holding voltage of the SRAM is 1.5-1.6 V,and the holding current is 9.9-11.2 mA.According to the holding current,holding voltage,working current and working voltage,judge whether circuit level protection can be adopted.Two circuit level protection methods of power supply current limiting and divider resistor were proposed,and the value range of power supply current limiting and divider resistor were calculated quantitatively.In the previous literature,resistor is only used as a means of current limiting after latch-up trigger,which can not prevent the device from latch-up.It is found that the divider resistor can also achieve the purpose of preventing the latch-up under certain conditions.The two protection methods were verified by pulse laser test.