Задача синтеза интегральных схем и основные сведения о КМОП технологии (1132262), страница 2

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Examples include minimum layout widths and spacing valuesbetween layout shapes.Electrical constraints ensure the desired electrical behavior of the design. Examples includemeeting maximum timing constraints for signal delay and staying below maximum couplingcapacitances.Geometry (design methodology) constraints are introduced to reduce the overall complexityof the design process. Examples include the use of preferred wiring directions during routing,and the placement of standard cells in rows.7312/30/2014Математические модели и методы синтеза СБИСЭвристические алгоритмыDeterministic: All decisions made by the algorithm are repeatable, i.e., not random. Oneexample of a deterministic heuristic is Dijkstra’s shortest path algorithm.Stochastic: Some decisions made by the algorithm are made randomly, e.g., using a pseudorandom number generator.

Thus, two independent runs of the algorithm will produce twodifferent solutions with high probability. One example of a stochastic algorithm is simulatedannealing.In terms of structure, a heuristic algorithm can beConstructive: The heuristic starts with an initial, incomplete (partial) solution and addscomponents until a complete solution is obtained.Iterative: The heuristic starts with a complete solution and repeatedly improves the currentsolution until a preset termination criterion is reached.7412/30/2014Математические модели и методы синтеза СБИСЭвристические алгоритмыProblem InstanceConstructive AlgorithmInitial SolutionIterative ImprovementnoTerminationCriterion Met?yesReturn Best-Seen Solution12/30/2014Математические модели и методы синтеза СБИС75Этапы развития САПР СБИСTime PeriodCircuit and Physical Design Process Advancements1950 -1965Manual design only.1965 -1975Layout editors, e.g., place and route tools, first developed forprinted circuit boards.1975 -1985More advanced tools for ICs and PCBs, with more sophisticatedalgorithms.1985 -1990First performance-driven tools and parallel optimization algorithmsfor layout; better understanding of underlying theory (graphtheory, solution complexity, etc.).1990 -2000First over-the-cell routing, first 3D and multilayer placement androuting techniques developed.

Automated circuit synthesis androutability-oriented design become dominant. Start of parallelizingworkloads. Emergence of physical synthesis.2000 - nowDesign for Manufacturability (DFM), optical proximity correction(OPC), and other techniques emerge at the design-manufacturinginterface. Increased reusability of blocks, including intellectualproperty (IP) blocks.12/30/2014Математические модели и методы синтеза СБИС76.

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