A transmission line delivers an output signal at a distance from the point of signal input. Any two conductors can make up a transmission line. The signal that is transmitted from one end of the pair to the other end is the voltage between the conductors. Power transmission lines, telephone lines, and waveguides are examples of transmission lines. Traces on printed circuit boards and multichip modules (MCMs) and within integrated circuits are other examples of transmission lines.
This chapter describes the basic transmission line simulation equations. It explains how to use these equations as an input to a transmission line model, the W Element. It also shows you an optional method of computing the parameters of the transmission line equations using the Star-Hspice field solver.
The W Element1 in Star-Hspice is a versatile transmission line model that can be applied to simulate from a simple lossless line to complex frequency-dependent lossy coupled lines with high efficiency and accuracy. Unlike the U Element discussed in Ideal and Lumped Transmission Lines, the W Element does not require fine-tuning of optional parameters that are needed to get accurate results.
However, transmission line simulation is challenging and time-consuming since extracting the transmission line parameters from physical geometry takes a significant effort. A simple but efficient and accurate 2-D electromagnetic field solver is newly introduced in Star-Hspice to calculate the electrical parameters of a transmission line based on its cross-section and makeup.
This chapter covers the following topics: