A Statistical Current and Delay Model Based on Log-Skew-Normal Distribution for Low Voltage Region

The increasing performance variation and non-Gaussian distribution pose remarkable challenges to timing analysis for circuits operating in low voltage region. Accurate modeling of the statistical characteristics is urgently required with process variation consideration. In this paper, the statistical models for drain current and gate delay in low voltage region are established in analytical form based on the log-skew-normal (LSN) distribution via moment matching technique. Experimental results show that the probability distribution function (PDF) curves obtained from the proposed models for drain current and gate delay are highly fitted with Monte Carlo (MC) simulation results in sub/near-threshold regions. Moreover, owing to the proposed LSN-based statistical model, less than 8% error is introduced in the predicted sensitivity of gate delay andthe maximum/minimum delay indicated by +/- 3 sigma percentile pointscan be calculated more precisely than the LN-based method with up to 3x accuracy improvement for low supply voltage.