Description

Printed Circuit Boards (PCBs) provide the primary signal interconnect medium in present computer systems. Silicon transistor technology is advancing at a pace predicted by Moore’s law. Signaling rates on PCB materials need to reach the Multi-Gigabits per second regime (over 25 Gb/s) to catch-up with the silicon technology. Increasing data-rates requires faster signal rise times pushing the interconnect bandwidth demand to the millimeter wave regime. As the Frequency content of the signals increase, micro scale structures of an interconnect medium, such as surface roughness of the copper and woven glass fabric reinforcements of PCB’s, can negatively influence the performance of PCB signal transmission. Advanced systems designs rely on rigorous Signal Integrity Simulation analysis to optimize for voltage and timing margin budgets. The nature of micro-scale periodic structures of PCB materials must be well understood and accounted in simulation models, especially at millimeter wavelength frequencies required to transmit high-speed digital signals. Empirical and analytical modeling techniques are being developed to model PCB transmission lines in the millimeter wave frequency ranges. This talk will explain the Electromagnetic wave propagation in a micro-scale periodic dielectric medium and its impact on multi-gigabit digital signal transmission. Special attention will be given to periodic loading effects due to glass fiber weaves in a PCB.