An Congestion-driven Placement Design Based On Macro

With the the development of Moore’s Law,integration of the chip continues to increase,density of circuit is increasing exponentially,and complexity of circuit is getting higher and higher,bringing a wide range of application scenarios and new challenges at the same time.In the field of EDA,it is not only necessary to advance together with advanced processes,but also to meet the requirements of process size reduction,wirelength,timing,and density.EDA technology is becoming more and more important.Placement is a key step in VLSI physical design flow and it determines the quality of the chip,including timing closure,silicon utilization,routability and the cycle time of the design.In the traditional algorirhm of placement,it takes reducing wirelength as target.But some standard cells which meet the grid density constraints and some macro may cause congestion.The chip can not be routed if there is too much congestion in routing.Therefore,it’s necessay to develop a congestiondriven placement.In this paper,we present a congestion-driven placement to estimating congestion which may occur in global placement and reducing congestion to improve routability.The main work is as follows:(1)Based on RUDY,a linear regression is performed to fit the coefficient of wirelength to get a fast and accurate wirelength throught HPWL.Computing the the area which net’s bounding box overlapping with bin to allocate routing demand reasonably for each bin.Thus,we are faster and more accurate to estimate congestion.(2)Based on the special target density balance method in Re Pl Ace,we propose a method for cell’s inflation without target density changing which reduces congestion that causing by standard cell affectively.(3)We present a macro inflating algorithm to fill full long channel which cause by macro to avoid standard cell being placed there to reduce congestion.(4)We present a net-based moving algorithm to push the net which in the congestion region to the a most closed share-net which has no congestion to reduce congestion which cause by net intersecting.(5)We present a framework for congestion-driven placement.It makes the wirelengthdriven placement 、 estimating congestion and congestion optimization working well.Not only has a good placement,but also routability in global placement.With the official protocol of evalution,our congestion-driven placer outperforms other published academic routability-driven placers.Compared with Replace,there has been a big improvement in both overflow and running time.Compared with top results in ISPD 2011 contest,our congestion-driven placer achieves a better solution.