Multi-stage analog placement with various constraints

In this paper, we present a placement method for analog circuit. This method can handle multiple constraints, which include multi-symmetry, proximity, signal-path clustering constraints. All these constraints are common requirement in analog circuit design. However, none of previous works considered the relations between constraints, and how to handle these multiple constraints effectively to get a convergent solution is also a seldom solved problem in previous works. Our contributions are threefold: 1) introduce signal path constraints and handle all constraints with Sequence Pair representation; 2) present a multi-stage simulated annealing strategy to acquire a faster convergence of searching process; 3) first introduce a post refinement stage to further improve the result placement, using linear programming. The effectiveness and efficiency of experimental results are promising.