Three-layer channel routing for standard cells with column-dependent variable over-the-cell routing capacities
Tetsushi Koide, M. Tsuchiya, Shin’ichi Wakabayashi, N. Yoshida · 2002
In this payer, we introduce a new three-layer standard cell model for over-the-cell routing, in which routing capacities on the second layer may vary column by column, and present a new over-the-cell channel routing algorithm, which can effectively utilize the over-the-cell region (OCR) of the proposed cell model. The proposed router performs two types of over-the-cell routing. For OCRs near the channel, it performs planar routing on the second and third layers. For OCRs far from the channel, it performs H-V routing on the second and third layers. Combining planar and H-V routings, the router can utilize OCR effectively, that could hardly be achieved by existing algorithms. We also formulate the problem of selecting planar routable nets on third layer as the maximum weighted planar routable net selection problem with nonuniform routing capacity, and propose an optimal algorithm.>