A gridless multi-layer area router

This paper presents an algorithm to route multiple nets for VLSI layout synthesis in the presence of irregular rectilinear obstacles. The proposed routing algorithms are to be used when layout is nearly finished. Any incremental routing for performance needs to be done by using the very limited space between existing layout cells or by routing directly over the cells. Each net has multiple pins, which are located either on the boundary or anywhere inside the layout region. The proposed algorithm is very systematic and easy to implement. It does not require any net sequencing, and through extensive experiments on real circuits has been shown to always produce near optimal solutions