To deal with the difficulties in optimal design for clock skew scheduling of SOC in very deep submicron integrated circuit, a novel useful clock skew scheduling based on particle swarm optimization (PSO) was presented to optimize circuit performance. This technique introduces useful skew in circuits and adopts adaptive PSO with linearly decreasing inertia weight to adjust the clock input delay of critical path. Global search is performed at useful clock skew that using worst negative slack as fitness function to find the optimal solution, consequently reduces the clock period and optimize the circuit performance. Compared with other existing graph based algorithms, the proposed technique can obtain better solution by optimizing the combinational path delays. The application to 32bit embedded CPU show that this algorithm is correct and effective.
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