US Patent 7315806 Enhanced negative constraint calculation for event driven simulations

A technique to enable accurate timing and functional verification in a negative constraint calculation (NCC) implemented event-driven logic simulators when there are negative constraints in logic elements. In one example embodiment, the technique adjusts negative timing constraints by grouping the timing constraints based on associated output terminals in a digital logic circuit. The NCC is then applied to each grouped constraint to correct for path delays and resulting timing inaccuracy during an event driven simulation.