Equalization for Electrical Links: Current Design Techniques and Future Directions

Another article in this issue, the introductory article by Tony Chan Carusone, discussed how the limited bandwidth of an electrical channel causes distortion (e.g., broadening) of the pulses traveling from transmitter to receiver. Without compensating for such distortion, the maximum data rate of a typical electrical link would be limited to only a few gigabits per second to avoid excessive intersymbol interference (ISI). The key to achieving dramatically higher data rates (up to 56 Gb/s in the latest proposed standards) is to employ channel equalization. This article describes the most common types of equalizers used in electrical links today.