An asynchronous data recovery/retransmission technique with foreground DLL calibration

A new technique for asynchronous data recovery based upon using a delay line in the incoming data path is introduced. The proposed data recovery system is well suited for tight tolerance channels and coding systems supporting standards that limit the maximum number of consecutive 0´s and 1´s in a data stream. The proposed system, which samples incoming data in the delay line on transitions of the data itself, has a reduced sensitivity to jitter on incoming data when compared to standard PLL-based data recovery systems. Further, the proposed technique actually recovers all data in the channel for a fixed interval prior to the first data transition. A system clock driven DLL is used to generate precise delays. This technique recovers the incoming data without recovering a clock signal. When used in a retransmitter, retimed data with a very low jitter that is essentially independent of the jitter on the incoming data stream is retransmitted