Method and apparatus for sampling point optimization

摘要

A method and apparatus for timing optimization are disclosed, which rely on information gathered from a timing detection circuit to find the optimal sampling point of a data recovery system. In an implementation, a timing shift is optimized based on Gardner detector data. In an example, a Gardner detector, or an early and late extraction portion thereof, is added to the data path, and the data path clock is shifted so that it is centered on the data transition mean. In an implementation, the sampling point of the data path is optimized for better horizontal eye opening using a Gardner detector's output for centering the average crossing point of different paths. In an example embodiment, an apparatus is provided with a second clock recovery that is not completely independent of a first clock recovery.

主权项

1. A method of optimizing a timing delay between a timing path and a data path, comprising:
a) adding a first programmable delay to a reference signal to produce a first delayed reference signal, the reference signal being generated by a timing recovery circuit in the timing path and synchronized with an average center of an eye of each bit period in an equalized input signal; b) adding a second delay to the first delayed reference signal to produce a second delayed reference signal; c) sampling the equalized input signal using the first and second delayed reference signals, the equalized input signal being generated by an equalizer in the data path; d) for each of a plurality of observed transitions in the equalized input signal, obtaining an early-late indication of whether an observed transition in the equalized input signal is early or late compared to an observed transition in the reference signal, based on the sampling, the observed transition in the equalized input signal being among the plurality of observed transitions in the equalized input signal; and e) adjusting the first programmable delay added to the reference signal based on the early-late indication.