Design advances in PCB/backplane interconnects for the propagation of high speed Gb/s digital signals

Abstract

Over the past five years tremendous advances have been made in the design of copper-based transmission line interconnects capable of propagating high-speed broadband digital signals over long lengths of printed circuit boards (PCBs) and backplanes. Data rates of 5 Gb/s transmitted over a single differential pair routed across more than one meter of PCB and backplane interconnect using low-cost FR-4 dielectric material is no longer all that unusual. And leading industry experts predict there is still plenty of bandwidth left to extend copper interconnects to well beyond 10 Gb/s. The high performance interconnects needed to sustain these high data rates are attained through the application of many different engineering design and manufacturing disciplines including active pre/post compensation circuits, cost effective mixed-dielectric PCB and backplane stackups, and innovative PCB via interconnect geometries. By applying these interdisciplinary technologies to the design of copper-based interconnects, signal attenuation and deterministic jitter distortions caused by frequency dependent interconnect materials and energy-storing geometric structures are minimized.