Two-Dimensional Routing for the Silc Silicon Compiler

This paper presents a new method for generating a two-dimensional routing for a class of custom integrated circuits (IC's). The method has been designed for Silc, an experimental silicon compiler currently under development at GTE Laboratories, and is suitable for the design of custom IC's composed of functional blocks. The method is based on an analytical model for generating a one-dimensional distribution of interconnections in irregularly shaped routing channels. The described procedure first determines the channel shapes that minimize the size of the layout and then allocates nets inside the channels while maintaining the required routing topology. One dimension of the layout is optimized at a time. Two-dimensional routing is obtained by coupling the minimization of the vertical and the horizontal dimensions of the layout with a set of additional constraints to ensure routing feasibility. The algorithm that implements this method has polynomial time complexity. The quality of the suboptimal results obtained with this method can be evaluated by comparison with the lower bounds obtained from independent, unconstrained linear programming solutions.