Characterization and design of sequential circuit elements to combat soft error

This paper performs analysis and design of latches and flip-flops while considering the effect of event upsets caused by energetic particle hits. First it is shown that the conventional analysis of this effect in sequential circuit elements (SCEs) tends to underestimate the threat posed by such events. More precisely, there exists a timing window close to the triggering edge of the clock during which a SCE is more vulnerable to the particle hit. This phenomenon has been ignored by previous work, resulting in false negatives. Next the paper explains how to size transistors of a familiar SCE i.e., a clocked CMOS latch, to make it more robust to such events. Experimental results to validate the characterization and transistor sizing steps are provided and discussed.