A hierarchical standard cell placement method based on a new cluster placement model

In this paper, we propose a new hierarchical timing-driven standard-cell placement method, in which a new cluster placement model is introduced. The proposed method is divided into three phases, clustering cells, global placement and detailed placement. After clustering cells, in the global placement phase, we determine and improve cluster placement by a simulated annealing based method. In most of previous methods, the shape of any cluster was restricted to a square. In the proposed method, however, we remove this restriction, and propose a new placement model, called the Amoeba model, in which the shape of a cluster can be a collection of connected squares. Since the flexibility of cluster placement is increased by the amoeba model, we can obtain a high quality placement satisfying timing constraints. In the detailed placement phase, we assign cells to cell rows under the non-overlapping constraint of cells with a constructive approach. Experimental results show the effectiveness of the proposed method with the new cluster placement model.