Layout migration is a fast methodology to generate the required layout for given circuits with different device attributes or different technology. By keeping the original layout topology, the previous design experience can help to keep the circuit performance. However, routing preservation is often not mentioned in previous layout migration techniques, which requires a complete rerouting to break the original style. Panet al.(2015) proposed a topological slicing tree and a constrained delaunay triangulation (CDT) model to keep the routing style during migration. However, this approach may incur some missing nets after migration, which still requires tedious manual works to fix those nets. In this article, we propose a sequence pair (SP)-based placement migration methodology and a novel Cartesian detection line (CDL) model to preserve the routing styles in original layouts. By using the proposed approach, the routability information and routing behaviors can be preserved during layout migration. In order to prevent from missing nets, several refinement techniques are also proposed to fix unreasonable routing nets due to block displacement. In the experiments, the missing nets after migration can be reduced to almost zero with the proposed CDL model, which greatly reduces the extra design efforts.

In order to improve design productivity, proper layout automation tools are desired for analog circuits. Layout migration is one possible approach to generate a new layout for given circuits with different device sizes or different technology, and still keep the original layout topology. However, routing behaviors are often not mentioned in previous works, which requires a complete rerouting that may not follow the original style. Pan [16] first proposed a Constrained Delaunay Triangulation (CDT) based model to keep the routing behavior during layout migration. However, because the device sizes and related distance may be different in the new layout, some reference lines in CDT models may be removed, resulting in some missing nets after migration. In this paper, a novel Cartesian Detection Line (CDL) based model is proposed to preserve the routing behavior in original layouts. Because alternative lines in the modified placement can be easily found to prevent from missing nets, the proposed CDL model greatly improves the routing completeness during layout migration. Several routing refinement techniques are also proposed to solve the routing issues due to block displacement. In our experiments, the routing completeness can be improved to almost 100% with the proposed CDL model, which greatly reduces the design efforts.