A Crosstalk-Friendly Signaling Method

As computer performance continues to increase at an exponential rate, the system bus bandwidth must scale in proportion. Increased bandwidth demands and smaller chassis sizes lead to a scenario where crosstalk noise becomes a primary limiter of bus performance. The goal of this paper is to remove the crosstalk bottleneck to allow very dense routing on printed circuit boards and packages, so the maximum computational capability can be designed into the smallest possible volume. This paper presents a new nonbinary signaling scheme called “crosstalk-harnessed signaling” (CHS) that encodes the data so that each bit is spread across multiple conductors in a way whereby crosstalk becomes part of the signal and can be removed during the decoding process. CHS can be implemented with relatively simple low-power circuits and can realize bus bandwidth gains over binary signaling as high as 2–3
${\times}$
while allowing
$2{\times}$
increase in routing density and increased pin efficiency compared to differential signaling. Finally, passive test board measurements corroborate simulations in demonstrating the benefits of CHS in crosstalk compensation over binary signaling to maximize the channel bandwidth density.