tailieunhanh - Handbook of algorithms for physical design automation part 47

Handbook of Algorithms for Physical Design Automation part 47 provides a detailed overview of VLSI physical design automation, emphasizing state-of-the-art techniques, trends and improvements that have emerged during the previous decade. After a brief introduction to the modern physical design problem, basic algorithmic techniques, and partitioning, the book discusses significant advances in floorplanning representations and describes recent formulations of the floorplanning problem. The text also addresses issues of placement, net layout and optimization, routing multiple signal nets, manufacturability, physical synthesis, special nets, and designing for specialized technologies. It includes a personal perspective from Ralph Otten as he looks back on. | 442 Handbook of Algorithms for Physical Design Automation cons. A hybrid approach is proposed recently 15 to combine the netweighting and net constraints together with LP-based formulations. Furthermore because of the complexity of modern placement problems and the iterative refinement nature from global placement to detailed legal placement it is very important to have stability between placement iterations. In this section we present several representative and recent techniques for TDP and timing-aware placement. Hybrid Net and Path-Based Approach In Ref. 15 a hybrid approach is proposed to combine the netweighting and net constraints together with LP-based formulations. The net-based approaches especially the netweighting have low computational complexity and high flexibility scalability. Therefore net-based approaches have more advantages as the circuit complexity continues to increase. However netweighting often completely ignores slew propagation. Because timing is inherently path based an effective netweighting algorithm should be based on path analysis and consider timing propagation. Furthermore net-based approaches are often done in an ad hoc manner and may have problems with convergence. For instance while the delay on critical paths decrease other paths become critical and this leads to a convergence problem. A systematic way of explicit perturbation control is important for netweighting-based algorithms. The hybrid approach in Ref. 15 uses a hybrid net and path-based delay sensitivity with limited-stage slew propagation as basis for netweighting. The objective function is the weighted wirelength for a set of critical paths. The LP formulation considers not only cells on the timing-critical paths but also cells that are logically adjacent to the critical paths in a unified manner through weighted LP objective function and net-bound constraints. This approach is suitable for incremental timing improvement. Hippocrates A Detailed Placer .