A New Metric for Estimating the Effects of Process Variability and Applications in Radiation-Tolerant Digital Circuits

In this work, the relationship between Lyapunov exponents, used to estimate the effects of process variability, and the standard deviation obtained through the Monte Carlo method was established analytically, demonstrating that the Lyapunov exponents characterize a metric for estimating such effects. Based on this, a new metric for estimating the effects of process variability, based on Lyapunov exponents, was developed. The Sum-Power-Delay (SPD) was analytically defined, and its application was verified in the design of an inverter using 180nm technology. The SPD was applied to compare two sets of twenty cells designed in 180nm and 180nm-RH, a radiation-tolerant cell library developed, demonstrating that cells designed with Enclosed Layout-Transistor (ELT) are more robust against process variability. A similar comparison and the same result was obtained when analyzing circuits from the ISCAS85 benchmarks, and for twenty circuits synthesized with our library. Finally, a set of RISC-V microprocessor cores designed with $180 ~\text{nm}$-RH transistors was evaluated to determine which core is the most robust to the effects of process variability.