Improved method of cell placement with symmetry constraints for analog IC layout design
Improved method of cell placement with symmetry constraints for analog IC layout design
复制标题
模拟 IC 布局设计中具有对称约束的改进单元布局方法
DOI：
10.1145/1123008.1123050
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
K. Fujiyoshi
中科院分区：
文献类型：
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作者：
S. Kouda;C. Kodama;K. Fujiyoshi
近年来，在高性能模拟IC设计中，经常需要将一些单元相对于水平或垂直轴对称放置。巴拉萨等人。提出了一种获得满足给定对称约束和序列对施加的拓扑约束的最接近布局的方法，但该方法具有以下缺陷：（1）一些单元相互重叠。 (2) 可能无法获得同时满足对称性和拓扑约束的最接近的单元布局。 (3)如何对称放置单元仅针对一个轴提及，对于多个轴没有说明。在本文中，我们提出了一种有效的方法来获得满足给定对称约束和使用线性规划的序列对施加的拓扑约束的最近单元布局。该方法从序列对中获得一个简单的约束图，并从该图中导出一组线性约束表达式。通过用因变量替换表达式来减少线性表达式的数量。然后通过线性规划得到解。计算实验证明了该方法的有效性。
Recently, it is often required in high performance analog IC design that some cells are placed symmetrically to horizontal or vertical axis. Balasa et al. proposed a method of obtaining the closest placement satisfying the given symmetry constraints and the topology constraints imposed by a sequence-pair, but this method has the following defects: (1) Some cells overlap each other. (2) The closest cell placement satisfying both the symmetry and topology constraints may not be obtained. (3) How to place cells symmetrically is mentioned only for one axis and there is no explanation for plural axes. In this paper, we propose an efficient method to obtain the closest cell placement satisfying the given symmetry constraints and the topology constraints imposed by a sequence-pair using linear programming. The proposed method obtains a simple constraint graph from a sequence-pair and derives a set of linear constraint expressions from the graph. The number of linear expressions decreases by substituting the expressions for dependent variables. Then the solutions are obtained by linear programming. The effectiveness of the proposed method was shown by computational experiments.