Elimination of mutual couplings in discrete element networks arising from the modeling of high speed digital interconnections

Ruehli et al. (1992) have presented a technique that allows an automatic derivation of equivalent discrete element networks for general interconnection structures that are valid up to very high frequencies. When we restrict ourselves to the lower frequencies that are typical for high speed digital circuits, then several approximations are possible. For the case of microstrip interconnection discontinuities, the authors have presented a possible reduction approach (1994). One of the consequences of the fact that we restrict ourselves to the low frequency range, is that a number of mutual couplings become redundant. This aspect has not been investigated. In this paper, we shall first explain where this redundancy comes from. Then, we shall present both a formal mathematical and a more practical approach for the elimination of mutual couplings in practical networks. We conclude this paper with an illustrative example