A multiple layer contour-based gridless channel router

An n-layer gridless channel router is presented. Instead of the commonly used grid it uses a set of contours as a routing framework. The contours, together with a set of reserved areas, present short circuits and ensure routability of all nets. A compact routing can be expected, since the framework is a very adequate model of the physical channel. It is shown that this router is also versatile enough to handle the classic vertical constraint problem. The inherent flexibility enables a design rule driven tradeoff between the number of vias, the wire length, and the channel height. The behavior of the algorithm has been investigated for many different channels, including the well-known difficult example and its recent derivatives. Very competitive results have been achieved for channel height and via count