Generalized Debye model for PCB dielectrics and conductors

Electromagnetic (EM) simulators are commonly used for electromagnetic compatibility and signal integrity (SI) analysis of printed circuit boards (PCB). The accuracy of such analysis depends on the models used for PCB dielectrics and conductors. These models should be broadband and preserve the physical properties of the materials, such as causality and passivity. One such model for dielectrics is the Debye model. Conductors have typically been modeled using a simple surface impedance formula, which is accurate for smooth conductors and small skin depth. With the evolution of high-speed designs, surface roughness loss has also become increasingly important for signal integrity of PCB interconnects. In this paper, we propose a Debye-like model for conductors possibly having rough surfaces. The advantages of a Debye model are its flexibility for arbitrary variation of surface roughness; guaranteed passivity in SI analysis; and availability of an equivalent circuit representation.