Density Smoothing Method Considering Wire-Length and Overlap

Current cell migration methods used in force-directed analytical placement have deficiency of damaging the results of last iterative placement and influencing the speed of convergence.In this paper, a new density smoothing technique called DSAW (density smoothing aware of wire-length) is presented.DSAW obtains the moving distance by both of the local and the global density distribution while considering the wire-length and overlap simultaneously, and tries to reduce the damage to the wire-length caused by cell migration.The standard cells and the macro blocks crossing multi-bin are separated and by summing the shifting vectors of the discrete modules so as to get a more smooth speed.DSAW is embedded into the global placement process of DPlace and replaces the original diffusion smoothing method, and experimental results show that average HPWL (half perimeter wire-length) reduces 7% and the total runtime is faster than original DPlace.