Routability Crossing Distribution and Floating Pin Assignment for T-type Junction Region

Abstract

Based on non-crossing relations, vertical constraint relations and net-geometry relations in one T-type junction region, two kinds of routability crossing distributions are proposed to improve routing performance in one T-type junction region. For routability crossing distribution in one T-type junction region, a routability-ordering graph is built to decide a net ordering in O(n2) time. For routability quota crossing distribution in one T-type junction region, if the number of net crossings in base channel is more than a given quota, this net ordering in routability crossing distribution will be further adjusted to satisfy the quota requirement by using a net interchange operation in O(n) time. For floating pin assignment in one T-type junction region, global nets are assigned on the boundary between top channel and base channel by interleaving vacant pins in O(n) time according to a net ordering in routability crossing distribution.