FD-TD MODELING OF DIGITAL SIGNAL PROPAGATION IN 3-D CIRCUITS WITH PASSIVE AND ACTIVE LOADS

Most existing computer-aided circuit design tools are limited when dig ital clock speeds exceed several hundred MHz. These tools may not deal effectively with the physics of UHF and microwave electromagnetic wav e energy transport along metal surfaces such as ground planes or in th e air away from metal paths that are common at or above this frequency range. In this paper, we discuss full-wave modeling of electronic cir cuits in three dimensions using the finite-difference time-domain (FD- TD) solution of Maxwell's equations. Parameters such as stripline comp lex line impedance, propagation constant, capacitance per unit length and inductance per unit length can be easily computed as a function of frequency. We also discuss FD-TD Maxwell's equations computational mo deling of lumped-circuit loads and sources in 3-D, including resistors and resistive voltage sources, capacitors, inductors, diodes, and tra nsistors. We believe that this approach will be useful in simulating t he large-signal behavior of very high-speed nonlinear analog and digit al devices in the context of the full-wave time-dependent electromagne tic field.