Performance limits of electrical cables for intrasystem communication

Abstract

Three types of cables (commercially available high-performance coaxial and ribbon cables, and an experimental flexible-film cable) were investigated for intrasystem communication in high-performance computer and communication systems. The electrical properties of the cables and their respective connectors were obtained and compared through the use of time-domain techniques. Feasibility for use in digital signal propagation at 500 Mb/s-1 Gb/s was demonstrated by means of pulse propagation and eye-diagram measurements. Performance limits in terms of maximum useful cable lengths were determined through simulations which included the effects of associated connectors, vias, and printed-circuit-card wiring. IntroductionCables will be required for intrasystem communication in forthcoming high-performance multiprocessor computers, in which individual processors are expected to function at clock rates of several hundred MHz. Similar needs are anticipated for forthcoming communication systems, which will have to carry digital signals at Gb/s data rates. In this

Electrical characteristics of interconnections for high-performance systems

“…What is of significance is tight signal integrity control. Generally, a 40-50% loss of the eye opening (40-50% of the available swing at the driver circuit output) or the area of the waveform in a predetermined "eye mask" (a time and amplitude window during the cycle time when data are being sampled) is associated with a reasonable minimum signal at the receiver to overcome all the noise sources discussed earlier [28], [29]. For a 500-Mb/s data rate, for example, a 2-ns-wide clean data interval has to be assured (4-ns repetition rate) while the path delay might be 10-20 ns.…”

“…Such cables have a nonuniform cross section, resulting in large variations in their electrical characteristics. Signal conductors narrower than 0.457 mm (18 mil) were found to be unable to provide connections longer than 2 m in the 1-Gb/s range [29], [30].…”