ABCD-NL: Approximating Non-Linear Analog/Mixed-Signal Systems using Purely Boolean Models for High-speed Simulation and Formal Verification

We present ABCD-NL, a technique that approximates non-linear analog circuits using purely Boolean models, to high accuracy. Given an analog/mixed-signal (AMS) system (e.g., a SPICE netlist), ABCD-NL produces a Boolean circuit representation (e.g., an And Inverter Graph, Finite State Machine, or Binary Decision Diagram) that captures the I/O behaviour of the given system, to near-SPICE accuracy, without making any apriori simplifications. The Boolean models produced by ABCD-NL can be used for high-speed simulation and formal verification of AMS designs, by leveraging existing tools developed for Boolean/hybrid systems analysis (e.g., ABC [1]). We apply ABCD-NL to a number of SPICE-level AMS circuits, including data converters, charge pumps, delay lines, comparators, etc. Also, we formally verify the throughput of a non-linear AMS signaling system – modelled in SPICE using 22nm BSIM4 transistors, Booleanized with high accuracy using ABCD-NL, and property-checked using ABC.