Low-order identification of interconnects with the generalized method of characteristics

This paper deals with the identification of low-order accurate macromodels describing electrically long lossy multiconductor transmission lines. The formulation is based on the generalized method of characteristics, whose key feature is the extraction of delays from the propagation operators. We describe and compare different delay extraction approaches, in view of the identification of the macromodels. In particular, we propose a new identification procedure enhancing the results coming from a vector fitting algorithm by a further nonlinear identification step. This gives more general properties to the model implementation (e.g., a state space realization with no repeated pole), possibly improving the accuracy at the same time. Some reference case studies are analyzed to highlight the key features of the proposed approach.