Circuit simulation based obstacle-aware Steiner routing

Steiner routing is a fundamental yet NP-hard problem, in VLSI design and other research fields. In this paper, we propose to model the routing graph by an RC network with routing terminals as input ports and Hanan nodes as output ports. We show that the faster an output reaches its peak, the higher the possibility for the correspondent Hanan node to be a Steiner point. Iteratively adding one or multiple selected Steiner points to build and improve Steiner trees leads to 1-cktSteiner and Blocked-cktSteiner (in short, B-cktSteiner) algorithms, respectively. When there are no routing obstacles, 1-cktSteiner obtains similar wirelength compared with the best existing algorithm FastSteiner. Both are less than 1% worse than the exact solution, but 1-cktSteiner is up to 11.3/spl times/ faster than FastSteiner. Compared with the fastest existing heuristic FLUTE, B-cktSteiner has similar runtime but up to 1.9% shorter wirelength. Different from FastSteiner and FLUTE which are only applicable to non-obstacle cases, 1-cktSteiner and B-cktSteiner can be applied to routing with obstacles with minimal runtime increase. Compared with the best existing obstacle-avoiding algorithm An-OARS Man, 1-cktSteiner has similar runtime and reduces wirelength by 6.12%. and B-cktSteiner has an average speedup of 352/spl times/ with a similar wirelength.