CMOS High-Speed I/Os — Present and Future

High-speed I/O circuits, once used only for PHYs, are now widely used for intra-system signaling as well because of their bandwidth, power, area, and cost advantages. This technology enables chips with over 1 Tb/s of I/O bandwidth today and over 10 Tb/s of bandwidth by 2010 as both signaling rates and number of high-speed I/Os increase with process scaling. Key technologies that enable this growth in I/O performance include low-jitter clock circuits and equalized signaling. An analysis of clock jitter and channel interference suggests that signaling rates should track transistor performance to rates of at least 40 Gb/s over boards, backplanes, and short-distance cables. 1