Congestion estimation during top-down placement

Congestion is one of the fundamental issues in very large scale integration physical design. In this paper, we propose two congestion-estimation approaches for early placement stages. First, we theoretically analyze the peak-congestion value of the design and experimentally validate the estimation approach. Second, we estimate regional congestion at the early stages of top-down placement. This is done by combining the wire-length distribution model and interregion wire estimation. Both approaches are based on the well-known Rent´s rule, which is previously used for wirelength estimation. This is the first attempt to predict congestion using Rent´s rule. The estimation results are compared with the layout after placement and global routing. Experiments on large industry circuits show that the early congestion estimation based on Rent´s rule is a promising approach