Rectilinear Steiner minimum tree (RSMT) problem asks for a shortest tree spanning a set of given terminals using only horizontal and vertical lines. Construction of RSMTs is an important problem in VLSI physical design. It is useful for both the detailed and global routing steps, and it is important for congestion, wire length and timing estimations during the floorplanning or placement step. The original RSMT problem assumes no obstacle in the routing region. However, in today’s designs, there can be many routing blockages, like macro cells, IP blocks and pre-routed nets. Therefore, the RSMT problem with blockages has become an important problem in practice and has received a lot of research attentions in the recent years. The RSMT problem has been shown to be NP-complete, and the introduction of obstacles has made this problem even more complicated. / In the first part of this thesis, we propose an exact algorithm, called ObSteiner, for the construction of obstacle-avoiding RSMT (OARSMT) in the presence of complex rectilinear obstacles. Our work is developed based on the GeoSteiner approach in which full Steiner trees (FSTs) are first constructed and then combined into a RSMT. We modify and extend the algorithm to allow rectilinear obstacles in the routing region. We prove that by adding virtual terminals to each routing obstacle, the FSTs in the presence of obstacles will follow some very simple structures. A two-phase approach is then developed for the construction of OARSMTs. In the first phase, we generate a set of FSTs. In the second phase, the FSTs generated in the first phase are used to construct an OARSMT. Experimental results show that ObSteiner is able to handle problems with hundreds of terminals in the presence of up to two thousand obstacles, generating an optimal solution in a reasonable amount of time. / In the second part of this thesis, we propose the OARSMT problem with slew constraints over obstacles. In modern VLSI designs, obstacles usually block a fraction of metal layers only making it possible to route over the obstacles. However, since buffers cannot be place on top of any obstacle, we should avoid routing long wires over obstacles. Therefore, we impose the slew constraints for the interconnects that are routed over obstacles. To deal with this problem, we analyze the optimal solutions and prove that the internal trees with signal direction over an obstacle will follow some simple structures. Based on this observation, we propose an exact algorithm, called ObSteiner with slew constraints, that is able to find an optimal solution in the extended Hanan grid. Experimental results show that the proposed algorithm is able to reduce nearly 5% routing resources on average in comparison with the OARSMT algorithm and is also very much faster. / Huang, Tao. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves [137]-144). / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- The rectilinear Steiner minimum tree problem --- p.1 / Chapter 1.2 --- Applications --- p.3 / Chapter 1.3 --- Obstacle consideration --- p.5 / Chapter 1.4 --- Thesis outline --- p.6 / Chapter 1.5 --- Thesis contributions --- p.8 / Chapter 2 --- Background --- p.11 / Chapter 2.1 --- RSMT algorithms --- p.11 / Chapter 2.1.1 --- Heuristics --- p.11 / Chapter 2.1.2 --- Exact algorithms --- p.20 / Chapter 2.2 --- OARSMT algorithms --- p.30 / Chapter 2.2.1 --- Heuristics --- p.30 / Chapter 2.2.2 --- Exact algorithms --- p.33 / Chapter 3 --- ObSteiner - an exact OARSMT algorithm --- p.37 / Chapter 3.1 --- Introduction --- p.38 / Chapter 3.2 --- Preliminaries --- p.39 / Chapter 3.2.1 --- OARSMT problem formulation --- p.39 / Chapter 3.2.2 --- An exact RSMT algorithm --- p.40 / Chapter 3.3 --- OARSMT decomposition --- p.42 / Chapter 3.3.1 --- Full Steiner trees among complex obstacles --- p.42 / Chapter 3.3.2 --- More Theoretical results --- p.59 / Chapter 3.4 --- OARSMT construction --- p.62 / Chapter 3.4.1 --- FST generation --- p.62 / Chapter 3.4.2 --- Pruning of FSTs --- p.66 / Chapter 3.4.3 --- FST concatenation --- p.71 / Chapter 3.5 --- Incremental construction --- p.82 / Chapter 3.6 --- Experiments --- p.83 / Chapter 4 --- ObSteiner with slew constraints --- p.97 / Chapter 4.1 --- Introduction --- p.97 / Chapter 4.2 --- Problem Formulation --- p.100 / Chapter 4.3 --- Overview of our approach --- p.103 / Chapter 4.4 --- Internal tree structures in an optimal solution --- p.103 / Chapter 4.5 --- Algorithm --- p.126 / Chapter 4.5.1 --- EFST and SCIFST generation --- p.127 / Chapter 4.5.2 --- Concatenation --- p.129 / Chapter 4.5.3 --- Incremental construction --- p.131 / Chapter 4.6 --- Experiments --- p.131 / Chapter 5 --- Conclusion --- p.135 / Bibliography --- p.137
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_328470 |
| Date | January 2013 |
| Contributors | Huang, Tao, Chinese University of Hong Kong Graduate School. Division of Computer Science and Engineering. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English |
| Detected Language | English |
| Type | Text, bibliography |
| Format | electronic resource, electronic resource, remote, 1 online resource (xi, 144 leaves) : ill. |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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