| Summary: | 碩士 === 國立中央大學 === 電機工程學系 === 101 === In recent years, several electronic-design automation (EDA) tools for placement are proposed and developed. Legalization is a very important stage for placing cells on legal positions. The existed methods for legalization usually try to minimize the total wire-length of cells. However, considering wire-length only in the placement stage is not sufficient for placing standard cells. A congested placement result may incur the routing difficult due to the congested problem in the placement rows. Therefore, legalization needs to consider the routability instead of the wire-length or displacement minimization.
In this thesis, we adopt a congestion map to indicate the usage of routing edges. Standard cells will be moved by forces to avoid overflow edges. In order to preserve the global placement result, the searching range is limited in the surrounding bins. Then, we use bin-based [15] legalization to find the positions of cells. Finally, we propose a cost function to search optimal position. To evaluate our proposed method, we use the benchmarks provided by ICCAD 2012 placement contest as experimental data. Experimental results show that the proposed method can produce better placement results that incur less overflows in the global routing stage.
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