Current wire length estimation techniques do not yet take into account multiterminal nets. Estimates are primarily based on a model for the circuit consisting only of point-to-point connections (two-terminal nets), where the number of such connections is generally “adjusted” to reflect the existence of multi-terminal nets. The influence of multi-terminal nets is then reduced to a scaling constant and barely reflects the situation in real circuits.
In the first part of this chapter, we try to find a good model for the partitioning behaviour of multi-terminal nets. Based on that model, we then deduct a net degree distribution. Experiments show that this distribution, based mainly on theoretical arguments, indeed resembles the net degree distributions found in actual circuits.
As a direct application of the multi-terminal net model, the second section investigates the possibility to generate synthetic benchmark circuits with characteristics similar to those of realistic circuits. The possibility of generating realistic benchmark circuits is necessary to be able to test CAD tools and to evaluate new computer architectures.
KeywordsLogic Block Output Terminal Benchmark Circuit Digital Design Realistic Circuit
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