The paper presents an efficient approach for the simulation of interconnects in high-speed circuits based on measured data or simulated EM data. The approach involves forming an initial transmission-line model based on a resonant approach introduced by the authors and subsequently tuning this model to match the measured data. Following tuning, the model is converted to a state-space formulation. This then enables a standard model reduction routine such as the Lanczos process to be applied so as to gain further improvements from a computational efficiency viewpoint. The overall result is a highly efficient interconnect model based on measured data.