Improving the Efficiency of Timing Simulation of Digital Circuits by Using Structurally Synthesized BDDs

Meeting timing requirements is an important constraint imposed on highly integrated circuits, and the verification of timing of a circuit before manufacturing is one of the critical tasks to be solved by CAD tools. In this paper, a new approach and the implementation of several algorithms to speed up gate-level timing simulation are proposed where, instead of gate delays, path delays for tree-like subcircuits (macros) are used. Therefore timing waveforms are calculated not for all internal nodes of the gate-level circuit but only for outputs of macros. The macros are represented by structurally synthesized binary decision diagrams (SSBDD) which enable a fast computation of delays for macros. The new approach to speed up the timing simulation is supported by encouraging experimental results.