Formal Timing Analysis of Digital Circuits

Abstract

Formal verification provides complete and sound analysis results and has widely been advocated for the functional verification of digital circuits. Besides the functional verification, a very important aspect of digital circuit design process is their timing analysis. However, despite its importance and critical nature, timing analysis is usually performed using traditional techniques, like gate-level simulation or static timing analysis, which provide approximate results due to their inexhaustive nature and thus may lead to an undesired functional behavior as well. To overcome these issues, we propose a generic framework to conduct the formal timing analysis using the Uppaal model checker in this paper. The first step in the proposed framework is to represent the timing characteristics of the given digital circuit using a state transition diagram in Uppaal. In this model, delays are integrated using the corresponding technology parameters and the information about timing paths is added using Quratus Prime Pro, which is used as a path extracting tool. The Uppaal timing model is then verified through TCTL properties to obtain timing related information, like maximum delay. For illustration purposes, we present the analysis of a number of real-world digital circuits, like Full Adder, 4-Bit Ripple Carry Adder, Shift Registers as well as C17, S27, S208, and S386 benchmark circuits.