A Simulation Framework for Analyzing Transient Effects Due to Thermal Noise in Sub-Threshold Circuits

Abstract

Noise analysis in nonlinear logic circuits requires models that take into account time-varying biasing conditions. When considering thermal noise, which moves the circuit away from its equilibrium point, a correct modeling approach has to go beyond the additive white Gaussian noise (AWGN) used in classical noise analysis. Even when accurate models are available, running standard Monte-Carlo simulations that will expose rare soft errors may still be computationally prohibitive. Probabilistic methods are often preferred for estimating the failure rate. However, these approaches may not provide any insight about the dynamic response to noise events. In this paper, we target both problems in the sub-threshold logic application domain. We first provide a time-domain model for fundamental, technology-independent thermal noise in sub-threshold circuits. Then, we use this model to generate noise input files for SPICE transient analysis. The effectiveness of the approach is demonstrated using 7nm FinFET predictive technology models (PTM) for an inverter and a NAND gate.