Handbook of Algorithms for Physical Design Automation part 49 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. | 462 Handbook of Algorithms for Physical Design Automation TABLE Netweighting for RISA Routability Model Pin Count Netweight q Pin Count Netweight q 1-3 15 4 20 5 25 6 30 7 35 8 40 9 45 10 50 Overflow with Look-Ahead Wang et al. tried a number of cost functions that cover both congestion and wirelength objectives 38 . Let WL be the total wirelength and OF be the total overflow of the current placement. The total overflow is the sum of overflow for all the placement bins. The overflow is the difference between routing demand and routing supply of the bin if demand is larger. The following seven cost functions are proposed Figure 1. WL total HPWL Figure 2. OF total overflow Figure 3. Hybrid 1 - a WL aOF 0 a 1 Figure 4. TimeHybrid 1 - aT WL aTOF a is changing during the placement process Figure 5. QL quadratic function when demand is smaller than supply linear function when demand is greater than supply Figure FIGURE Cost function versus number of crossing nets on each global bin. Congestion-Driven Physical Design 463 6. LQ linear function when demand is smaller than supply quadratic function when demand is greater than supply Figure 7. Look-Ahead start considering congestion cost when demand is close enough to supply All these cost functions are experimented in both global placement and detailed placement stages. The authors found that during global placement none of the objectives works well except total wirelength. However in detailed placement stage several cost functions are reasonably good and LookAhead gives the best result in terms of congestion. A-Tree Router Chang et al. integrate a fast A-tree router into a multilevel simulated-annealing global-placement engine called mPG 8 . mPG is inspired by the recent success of the multilevel methods in efficiently handling bipartitioning
