Lossy Transmission Line Model Based on the Generalized Method of Characteristics

In this paper, an approach for obtaining the rational approximations used in the generalized Method of Characteristics (MoC) transmission line model is developed. Vector fitting is done offline and the proposed model is obtained analytically using predetermined rational coefficients, the per-unit-length parameters, and the line length. The algorithm is developed for two-conductor transmission line structures with frequency-independent per-unit-length parameters with negligible conductance effects. It is shown that the proposed methodology can provide more accurate results for challenging line modelling problems, such as very long transmission lines, when compared with HSPICE’s W-Element.

I. Introduction

Modeling transmission lines accurately is important for transient analysis when determining near and far-end voltage measurements for power application, on-chip, and printed circuit board interconnect modelling. Transmission line transfer function solutions are easily calculated in the frequency domain; however, the difficulties in finding corresponding time domain solutions lead to challenges in finding accurate time domain models.