A size-balancing approach to mixed mode placement

Mixed mode is a combination of standard cell and macro block, which is an often-occurred situation in practice. Existing flat and hierarchical algorithms suffer either bad quality or high complexity when coping with the great difference of component size. Further more, even the state-of-the-art placement algorithms are becoming incompetent with the rapidly increasing of the number of placement components. In this paper, an efficient scheme for mixed mode placement is presented. The scheme is named BMMP (Balanced Mixed Mode Placer) because it first does a clustering procedure to the original circuit to obtain a set of new placement components with balanced size. Then a quadratic global placement procedure is applied to the condensed circuit to achieve a cluster-level solution with global optima. At the end of global placement, the macro blocks are restored to their original shape, and the overlaps among them are resolved by a SP (Sequence Pair) based procedure. Placement improvement is then done to both the macro blocks and standard cells by moving them to their optimal locations. At last, a detailed placement procedure completes the final placement without any overlap. The algorithm is tested on a set of circuits with different number of standard cells and macro blocks, and obtains excellent results.