Clock recovery for data signals

摘要

Embodiments of the present invention provide improved techniques for recovering clock information from data signals. In one embodiment, a general purpose device such as a real-time oscilloscope acquires a data signal. The device takes a derivative of the data signal, then computes the square or absolute of the derivative before applying a bandpass filter. The bandpass filter is a windowing function a spectrum that is wider than the clock, and has a flat top and smooth transitions on both sides. In one embodiment, at Tukey window may be used. The device finds edge crossing times of the filtered result, and applies a phase-locked loop or lowpass filter to the edge crossing times in order to recover a stable clock signal. When the improved techniques are implemented in software, they may be used with any number of different equalizers that are required by various high-speed serial data link systems.

主权项

1. A test instrument configured to recover a clock signal from a data signal, the instrument comprising:
a physical interface for acquiring data signal information from the data signal; memory configured to store:
the data signal information;a recovered clock signal; andsoftware instructions for performing a clock recovery method, the method comprising:
computing a derivative of the data signal information;computing a square or absolute of the derivative;obtaining a filtered result by applying a bandpass filter to the square or absolute;finding one or more edge crossing trifles of the filtered result;filtering the one or more edge crossing times to obtain a recovered clock signal; andstoring the recovered clock signal in the memory; and a processor configured to execute the software instructions.