Computation of passive and compact macromodels of distributed interconnects has gained considerable importance during the recent years. Method of characteristics (MoC) is widely used for macromodeling of transmission lines, however, it may not be guaranteed passive. This paper presents a new algorithm for passivity enforcement of MoC-based macromodels of multiconductor transmission lines. The algorithm is based on the first-order perturbation of the related delay differential equations and can handle single as well as coupled interconnects. Necessary theoretical foundations and validating numerical results are presented.

This paper presents a robust method for guaranteed passive macromodeling of high-speed interconnects characterized by multiconductor transmission lines with frequency-dependent per-unit-length (FD-PUL) parameters, using integrated-congruence-transformation-based model-order-reduction techniques. For this purpose, a new formulation is developed to directly incorporate state-space equations corresponding to the positive-real (PR) rational functions representing the frequency dependence of PUL parameters, in Telegrapher's equations. The proposed formulation overcomes the need for explicit lumped-circuit realization with all positive elements for PR rational functions of FD-PUL parameters. Proof of passivity and numerical examples are presented to validate the theory.

This paper describes a new algorithm for the analysis of high-speed interconnects characterized by frequency-dependent per-unit-length parameter matrices. The proposed technique is based on using the idea of integrated congruence transform to construct a reduced-order system for the interconnect. The reduced-order system offers simple time-domain ordinary differential equations that can be embedded into conventional circuit simulators. The proposed algorithm provides a new approach to perform implicit moment matching on a system described by a mixed set of linear differential algebraic equations. This feature offers a high accuracy in the reduced system over a wide frequency range. The passivity of the reduced-order system is guaranteed. Numerical results demonstrate the validity of the proposed technique.