Claims
- 1. A method for auto-skew alignment of high-speed differential eye diagrams, said method comprising:
providing a pair of time-dependent differential signals related to one another by a differential timing skew; constructing mathematical functions dependent on magnitudes of said differential signals and said differential timing skew; defining a figure of merit containing time integrals of said mathematical functions; and calculating an optimized value of said differential timing skew such that said figure of merit reaches a minimum value.
- 2. The method of claim 1 further comprising applying said optimized value of said differential timing skew to align the skew of high-speed differential eye diagrams involving said pair of time-dependent differential signals.
- 3. The method of claim 1 further comprising scaling said pair of time-dependent differential signals such that integration of said time integrals is performed over a random time interval including at least two consecutive bit periods of said pair of time-dependent differential signals.
- 4. The method of claim 1 further comprising acquiring the values of said differential signals and said differential timing skew using hardware instrumentation.
- 5. The method of claim 4 wherein the accuracy of said optimized value of said differential timing skew is limited only by skew resolution of said hardware instrumentation.
- 6. The method of claim 5 wherein said accuracy is less than or equal to one picosecond.
- 7. The method of claim 1 wherein said calculating is performed substantially automatically.
- 8. The method of claim 7 wherein said calculating includes a coarse search for said optimized value of said differential timing skew.
- 9. The method of claim 8 wherein a user-selectable coarse skew interval is inputted prior to said calculating.
- 10. The method of claim 7 wherein said calculating includes a fine search for said optimized value of said differential timing skew.
- 11. The method of claim 10 wherein said fine search is performed using an adaptively decreasing fine skew interval.
- 12. A system for auto-skew alignment of high-speed differential eye diagrams of a pair of time-dependent differential signals related to one another by a differential timing skew, said system comprising:
paired skew circuits operable to delay each of said time-dependent differential signals independently; paired sampling circuits interconnected with said paired skew circuits, said sampling circuits operable to sample the waveforms of said time-dependent differential signals independently; a timebase generator operable to generate a common measurement timebase; and a processing unit operable to perform mathematical calculations using data acquired by said paired sampling circuits in accordance with an auto-deskew algorithm.
- 13. The system of claim 12 wherein said timebase generator is incorporated within an instrument mainframe.
- 14. The system of claim 12 wherein said paired sampling circuits are incorporated within a digital communications analyzer.
- 15. The system of claim 12 operable with a skew resolution of less than or equal to one picosecond.
- 16. The system of claim 12 wherein said processing unit is operable to construct mathematical functions dependent on said acquired data.
- 17. The system of claim 16 wherein said processing unit is operable to calculate a figure of merit containing time integrals of said mathematical functions.
- 18. The system of claim 17 wherein said processing unit is operable to calculate an optimized value of said differential timing skew such that said figure of merit reaches a minimum value.
- 19. The system of claim 18 wherein the accuracy of said optimized value of said differential timing skew is limited only by skew resolution of said acquired data.
- 20. The system of claim 12 wherein said processing unit is operable to perform substantially automatically in accordance with said auto-deskew algorithm.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is related to co-pending and commonly assigned U.S. patent application Ser. No. ______ [Docket No. 10020711-1, Attorney Docket No. 56721-P052US-10208590] entitled “VARIABLE DATA RATE BIT ERROR MEASUREMENTS USING BIT REPLICATION,” the disclosure of which is hereby incorporated herein by reference.