Simulation-Based Approaches for Comprehensive Schmitt-Trigger Analyses

Schmitt-Triggers (S/Ts) are often utilized to clean noisy analog signals at intermediate voltage values in digital circuits. However, they are vulnerable to metastability, which may cause the same undesired non-digital output behavior that was supposed to be removed in the first place. To enable an efficient characterization of static and dynamic metastability properties of S/Ts (e.g., the metastable voltages, the resolution time constants and the overall total resolution times), this work introduces multiple simulation approaches based on control theory, AC, DC and transient analyses. The accuracy and runtime of all methods are compared and discussed by applying them to an analytically describable idealized circuit model as well as three common circuit implementations. Altogether, this work represents a comprehensive resource for investigating the metastable behavior in S/Ts. Even more, the proposed methods are applicable beyond the S/T, enabling an efficient characterization of static and dynamic metastable behavior in general circuits as well.