In this paper we propose a general framework for viewing a class of heuristics for track assignment in channel routing from a purely graph theoretic angle. Within this framework we propose algorithms for computing routing solutions using optimal or near optimal number of tracks for several well-known benchmark channels in the two-layer VH. Three-layer HVH, and multi-layer V/sub i/H/sub i/ and V/sub i/H/sub i+1/ routing models. Within the same framework we also design an algorithm for minimizing the total wire length in the two-layer VH and three-layer HVH routing models.

A general graph theoretic framework for multi-layer channel routing

NP-Completeness of Multi-Layer No-Dogleg Channel Routing and an Efficient Heuristic

This paper presents a new channel routing algorithm that uses three restricted reserved layers,- either VHV or HVH, where H- and V-layers are used for horizontal and vertical segments of the nets present in the channel. Connections between two adjacent layers are made through via holes. The algorithm utilizes some derivatives of both the channel constraint graphs in the form a maxed graph. The net mergang operaiion is inherent. Individually both the cases of no- dogleg and restricted dogleg can be taken into account. The complexity of the algorithm is O(n2), where n is the number of nets (no-dogleg) or the number of subnets (restricted dogleg). 100% routing solution is always guaranteed even an the presence of cycle in the VCG.

An Efficient Graph-Theoretic Algorithm for Three-Layer Channel Routing

An algorithm for finding a non-trivial lower bound for channel routing

Channel routing problem is a problem in VLSI physical design whose objective is to compute a feasible minimum area routing solution. A channel is a rectangular routing region where the terminals are usually present on two of its opposite sides, and the other two sides are open ends. Routing is the task to interconnect all the nets present in a channel obeying constraints within the channel region. A net is a set of terminals that need to be electrically connected (usually using rectilinear wiring). The two important constraints present in a channel are horizontal constraint and vertical constraint. In this paper we visualize these two constraints through graphs in a different way, and combinedly use them to compute reduced area channel routing solutions.

Gregory A. Schaper

Papers

Multi-layer channel routing