Overview

Now it is time to consider some practicalities of how you will actually implement a design that transports data at microwave frequencies. This material will be more of the same old thing in the sense that those who have been working in the lower few hundred megahertz have mostly been analyzing their signal integrity with various SPICE implementations. As you now move into the gigahertz realm, you will still find SPICE the workhorse of signal integrity analysis. You need answers to three questions: When are SPICE simulations valid? What does a simulation tool need to yield good results? And, what do you do with problems that are outside the capabilities of SPICE simulators?

This chapter explores modeling alternatives and issues that cannot be directly resolved by a SPICE simulator, even though it is not yet time to abandon SPICE. Enhance your ability with SPICE tools by learning how to cast problems in terms that SPICE can simulate. The slow field solvers may be correct for some structures, but they can also be used to generate models that are useful in SPICE simulations. The underlying reality is that a simple problem, such as 10 inches of differential trace with a connector in the middle, can be modeled in seconds with SPICE, and can take hours in a 3D full-wave field solver. Real engineers need to be productive; you cannot afford slow tools in cases that don't mandate such.