US Patent 7546494 Skew-correcting apparatus using dual loopback

An apparatus for determining the amount of skew injected into a high-speed data communications system, including a plurality of lanes having a data bus per lane, relative to a reference lane, for system skew compensation. By knowing the relative amount of skew that each lane requires for alignment, an appropriate amount of skew is then injected on each lane to provide alignment and thus compliancy with the SFI-5 and SxI-5 standards, in terms of data skew specifications. The relative skew amounts for each transmitting lane are determined using dual loopback methods.