CUHK electronic theses & dissertations collection

For the congestion issue, we found that the existing congestion models will very often over-estimate the congestion at the densely routed regions because real routers will perform rip-up and re-route operations and route the nets with detour to avoid overflow. We propose a 3-step approach that is designed to tackle this problem. It can simulate the global routing, detailed routing and rip-up and re-route process in the real routing procedure. Results show that the prediction accuracy can be improved by 30%. In addition, we have also implemented a routability-driven floorplanner with our congestion model. Results show that the number of un-routable wires can be reduced if the number of overflow tiles can be reduced during floorplanning. Then we studied and developed two post-processing steps to be applied on an interconnect optimized floorplan or placement to further reduce the total wirelength or area. For the wirelength issue, we presented an elegant solution to the cell flipping problem. We presented a detailed study of this cell flipping problem in a placement result to reduce interconnect length. We find the optimal flipping of the cells by formulating the cell flipping problem as a mixed integer linear programming problem to give the shortest total wirelength. In order to reduce the runtime, we proposed a cell orientation fixing step to fix the orientations of some cells. Results show that we can obtain optimal result by solving the mixed integer linear programming problem of the remaining variables directly or the problem can be solved by linear programming such that we can still obtain a result very close to the optimal solution with a much shorter runtime. For area reduction on an interconnect optimized floorplan, we proposed a new approach called deadspace utilization to reduce the total area of an interconnect optimized floorplan by making use of the shape flexibility of some modules. Results show that we can apply this deadspace utilization technique to reduce the area and wirelength of the original floorplan further, subject to the constraint of maintaining the routability and congestion of the original floorplan.We have studied several interconnect-related optimization problems in floor-planning and placement of VLSI circuits in details. When the number of small logic gates is large in a circuit design, good netlist designs may still result in poor layouts because of various interconnect problems. Most of the problems cannot be fixed manually today because of the incomprehensible circuit complexity. Design automation techniques on interconnect issues in physical design of VLSI circuits becomes indispensable. Recently, congestion minimization and wirelength optimization are two hot topics in interconnect planning.Sham Chiu Wing."March 2006."Adviser: Young Fung Yu.Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6634.Thesis (Ph.D.)--Chinese University of Hong Kong, 2006.Includes bibliographical references (p. 106-115).Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.Abstracts in English and Chinese.School code: 1307