Complex communication and information systems operating in the Gigahertz range often combine multiple analog and digital functions. The design of such systems must capture all electromagnetic effects and interactions that impact their performance. However, it is impossible to model such systems globally at the field and device levels. Therefore, designers must take a hierarchical approach (top-down design) by which the system is conceived at a high level of abstraction and in behavioral terms. The specifications for its functional components are formulated at the network or circuit level. They, in turn, define a physical structure that requires frequency- or time-domain electromagnetic field analysis. Once the functional components have been realized, their actual physical behavior must be analyzed or measured, including possible parasitic
interactions between them, and abstracted into realistic (as opposed to initially specified) behavioral models that accurately predict their impact on overall system performance (bottom-up verification). This methodology also addresses signal integrity, packaging, interconnects, electromagnetic compatibility (EMC), and thermal issues.
The purpose of this lecture is to familiarize our members with evolving design approaches for systems of large technological and functional complexity, and to demonstrate how microwave modeling and design practices can be integrated into a wider flexible multi-level modeling environment. Techniques for interfacing models at the behavioral, network, circuit and field levels will be demonstrated. They range from order reduction of field models to the coupling of field- and circuit solvers, extraction of equivalent circuits from field solutions and measurements, behavioral representation by neural networks, and the linking of electromagnetic and thermal solvers. The key is to describe different parts of a complex structure by the most appropriate model of lowest possible order, while maintaining a two-way correspondence between functional behavior and physics across the modeling hierarchy.