Correlations between Static Noise Margin and Single-Event-Upset Hardness for SRAM Cells

The correlations between static noise margin (SNM) and single-event-upset (SEU) hardness for static random access memory (SRAM) cells are investigated in detail by comparing the values of the SNM with corresponding SEU thresholds of the SRAM cell for the different width values of the transistors of the cell, based on SPICE simulations. The results show that there is a positive correlation between the SNM and the SEU hardness of the cell, when the change for the widths of the two p-channel transistors is the same. At the same time, the results also reveal that a negative correlation exists between the SNM and SEU hardness of the cell, when the widths of the two n-channel transistors have the same change, and the width of the p-channel transistor is kept constant. In addition, it is also found that the cell SEU hardness is much more sensitive to the change of the width of the p-channel transistors than that of the n-channel ones, and the change in the width of the p-channel transistors is dominant in affecting the SNM, compared to that in the n-channel transistors, and hence the correlations between the SNM and SEU hardness.