TermMerg: An Efficient Terminal-Reduction Method for Interconnect Circuits

Abstract

In this paper, a novel method to efficiently reduce the terminal number of general linear-interconnect circuits with a large number of input or output terminals considering delay uncertainty is proposed. Our new algorithm is motivated by the fact that terminal reduction can lead to a more compact order-reduced model and the observation that very large-scale integration interconnect circuits have many similar terminals in terms of their timing and delay metrics due to their closeness in structure or due to the mathematical discretization using meshing in finite-difference or finite-element scheme during the extraction process. The new method, called TermMerg ( Proc. ICCAD, p. 821, 2005), is based on the moments of the circuits as the metrics for the timing or delay. It then employs a singular-value-decomposition (SVD) method to determine the best number of clusters based on the low-rank approximation. After this, the -means clustering algorithm is used to cluster the moments of the terminals into the different clusters. The proposed method can work with any passive-model order reduction and ensure the passive models. In contrast, we show that singular value decomposition model order reduction (SVDMOR) does not generate passive models in general. Passivity enforcement in SVDMOR will significantly hamper the terminal-reduction effectiveness. Experimental results on a number of real industry interconnect circuits demonstrate the effectiveness of the proposed method and show also that the proposed method is more accurate than SVDMOR when the used moment matrix does not give good terminal correlations.