High-performance electrical signaling

This paper reviews the technology of high-performance electrical signaling, presents the current state of the art, and projects future directions. We have demonstrated equalized electrical signaling between CMOS integrated circuits at data rates of 4Gb/s. As the factors that determine this signaling rate all scale with improving technology, we expect the data rates of high-performance electrical signaling systems to improve on a Moore's Law curve. The frequency-dependent attenuation of copper wires sets a bandwidth-distance squared (Bd(2)) limit on the distance one can signal at a given data rate. Equalizing the channel cancels inter-symbol interference caused by this attenuation and greatly increases signaling distance. In the limit of perfect equalization, distance is ultimately limited by thermal noise in the receiver. At this limit, we calculate that a 4Gb/s system will be capable of operating over 100m of 24-gauge cable without repeaters.