Minimizing Impedance Discontinuities In High-speed Pcb Designs

摘要

A growing number of high-speed standards and proprietary serial protocols are posing major design layout challenges for PCB designers. These serial standards include PCI Express, Serial RapidIO, Gigabit Ethernet, XAUI/HiGig, SONET, CPRI, OBSAI, and a host of others. Serial buses with differential signaling are quickly replacing parallel buses as the demand for high-speed PCB designs increases. Differential signaling uses two output drivers to drive two independent transmission lines. One carries one bit; the other, its complement. The difference of the two signals measured between the two traces carries the information. A differential pair is a pair of transmission lines with some amount of coupling between the two legs of the pair.