Effect of Critical Path Minimization on Total Wire Length for Unequal Sized Recursive Min-Cut Placement

In this paper, the effect of critical path minimization on wire length is examined for a new method of min-cut partitioning. Traditional min-cut placers use equal sized partitioning for VLSI placement. They use either bisection or quadrisecton to divide the circuit. This paper gives an introduction to a new method of partitioning called unequal sized partitioning. In this method of unequal sized min-cut partitioning the circuit is recursively divided into unequal sized partitions. Firstly an introduction to unequal sized recursive partitioning is presented. Then the net weights on the critical path are varied for MCNC benchmark circuits for different partition ratios ranging from 0.1 to 0.9 and the placement results are examined. The results prove that each circuit has optimal wire length at different partition ratio for a different critical path weighting. Finally this paper suggests the need for unequal sized partitioning which improves the wire length significantly as compared to the conventional equal sized partitioning. Keywords— critical path, net weighting, min-cut algorithm, placement, unequal sized partitioning

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