Efficient analytical determination of the SEU-induced pulse shape

Single event upsets (SEUs) have become problematic for both combinational and sequential circuits in the deep sub-micron era due to device scaling, lowered supply voltages and higher operating frequencies. To design radiation tolerant circuits efficiently, techniques are required to analyze the effects of a radiation particle strike on a circuit early in the design flow, and hence evaluate the circuit´s resilience to SEU events. For an accurate estimation of the SEU tolerance of a circuit, it is important to consider the effects of electrical masking. This is typically done by performing circuit simulations, which are slow. In this paper, we present an analytical model for the determination of the shape of radiation-induced voltage glitches in combinational circuits. The output of our approach can be propagated to the primary outputs of the circuit using existing tools, thereby modeling the effects of electrical masking. This enables an accurate and quick evaluation of the SEU robustness of a circuit. Experimental results demonstrate that our model is very accurate, with a very low root mean square percentage error in the estimation of the shape of the voltage glitch of (4.5%) compared to SPICE. Our model gains its accuracy by using a non-linear model for the load current of the gate, and by considering the effect of tau_beta on the radiation induced voltage glitch. Our analytical model is very fast (275 times faster than SPICE) and accurate, and can therefore be easily incorporated in a design flow to estimate the SEU tolerance of circuits early in the design process.