Parasitic-Aware Optimization and Retargeting of Analog Layouts: A Symbolic-Template Approach

Layout parasitics can significantly affect the performance of analog integrated circuits (ICs). In this paper, a systematic method of optimizing an existing analog layout considering parasitics is presented for technology migration and performance retargeting. This method represents the locations of layout rectangle edges as variables and extracts circuit and layout integrity such as device symmetry, matching, and design rules as constraints. To ensure the desired circuit performance, bounds of layout parasitics are determined first. These bounds are used to constrain the layout geometries while retargeting existing high-quality layouts across technologies and specification sets. The problem is then solved by a graph-based algorithm combined with nonlinear optimization. The proposed method has been implemented in a parasitic-aware automatic layout optimization and retargeting tool (intellectual property reuse-based analog IC layout). Its efficiency and effectiveness are demonstrated by successfully retargeting operational amplifiers within 1 min of CPU time.