A Robust Multilayer X-Architecture Global Routing System Based on Particle Swarm Optimization

Global routing is an extremely important stage of very large scale integration (VLSI) physical design. With the rise of nano-scale integrated circuit design, the multilayer global routing problem has attracted considerable research interest during the past few years. In this article, a multilayer X-architecture global routing (ML-XGR) system based on particle swarm optimization (PSO), called FZU-Router, is proposed to solve the ML-XGR problem for the first time. FZU-Router contains a multilayer X-architecture integer linear programming (MX-ILP) model and a multilayer X-architecture PSO (MX-PSO) algorithm, which are presented to formulate and solve the ML-XGR problem, respectively. Moreover, four effective strategies are designed to enhance the efficiency of FZU-Router: 1) a strategy for generating new routing modes is proposed to strengthen the robustness of encoding strategy of MX-PSO; 2) a strategy for combining MX-PSO with maze routing is proposed to improve the routability; 3) a strategy for reducing the channel capacity is proposed to make better use of optimization ability of MX-PSO; and 4) a strategy for dynamic resource assignment is proposed to make better use of routing resources and shorten the running time. Experimental results on multiple benchmarks confirm that the proposed FZU-Router leads to fewer total overflow and shorter total wirelength compared with the state-of-the-art routers.