Modeling and Simulation of High-Speed Digital Circuit Interconnections

Abstract

The advent of fast devices and the demand for smaller integrated circuits and packages have led to a high density of components and closely packed interconnects in both on-chip and off-chip levels. Size and spacing of interconnects have been dramatically reduced in recent years which have led to various electrical phenomena involving waveform distortion attenuation, and crosstalk causing a higher level of noise and possibly data error in fast computer or telecommunication networks.

The modeling of interconnections and the simulation of transients are of prime importance in the performance evaluation of a high-speed digital circuit and the design process requires accurate and efficient algorithms and analytical models. This study concentrates on the characterization of interconnections (with special emphasis on microstrip) and the simulation of transients in single or coupled transmission lines. In order to simulate the actual situation, dispersion, line losses, and nonlinear and reactive terminations must be treated. Frequency domain methods in which the boundary conditions are applied in the frequency domain are first used to simulate a variety of cases involving losses and reactive terminations.

For the more complex case involving nonlinear terminations, the time-domain scattering parameter approach is developed and applied. Iterative methods and numerical integration schemes are combined to describe the most general situation involving all types of terminations. Comparisons of simulations with experimental waveforms are performed to demonstrate the accuracy of these algorithms.