HFAN-06.0.1: Equalizing Gigabit-per-Second Signals on Copper Media

Abstract

Several equalizer techniques are available for achieving signal integrity in Gigabit-per-second NRZ links on low-cost copper transmission line media, including FR-4 PCBs and coaxial cable. The most commonmethods are passive networks, adaptive receive equalization, and pre-emphasis. Use of these techniques normally involves a number of important tradeoffs, including performance, flexibility, EMI/EMC, media cost, and compatibility with standard signal formats such as SONET, Fiber Channel and Ethernet. This note provides an overview and comparison of practical methods to equalize Gigabit-per-second NRZsignals in applications, including OC-48/OC-192, XGbE and 10G FC systems, or anywhere dielectric lossand skin effect create unacceptable amounts of intersymbol interference. The results are applicable to a variety of interconnects, including backplanes, cable interconnects and 10G pluggable serial modules.