Alignment jitter accumulation in a chain of processing node regenerators

It is shown that significant accumulation of alignment jitter can result if there exists any difference between signal and timing paths in respective regenerators in a chain. This phenomenon of extra alignment jitter accumulation is analyzed by using the Chapman model. The dependence of accumulation on timing extractor and delay difference is predicted through the theoretical analyses. Results of computer simulation are found to be in good agreement with theory. It is also revealed by the simulation that additional accumulation can be entailed which is explained in terms of jitter fine structures. It is suggested that the use of a scrambler, Q-M value selection, or delay compensation in the timing path can be applied to alleviate the problem of excess alignment jitter accumulation. Design considerations for time cross-hair budget are also discussed.<
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