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https://designers-guide.org/forum/YaBB.pl Design >> High-Speed I/O Design >> relation between group delay variation and horizontal eye closure https://designers-guide.org/forum/YaBB.pl?num=1260890334 Message started by vivkr on Dec 15th, 2009, 7:18am |
Title: relation between group delay variation and horizontal eye closure Post by vivkr on Dec 15th, 2009, 7:18am I have a front-end which has rather significant group delay variation when I perform an AC sim. The group delay varies from lower to higher frequencies within the band of interest by about 25% of the bit period. I would logically expect that a PRBS simulation would show the eye closing in the X-direction by a similar amount. However, such a PRBS-sim shows negligible closure in the X-direction. I have checked that I really do have a PRBS input, and that I have taken a large enough number of samples (5000 or so). Is my understanding of the relationship between group delay variation and eye closure incorrect ? Note: The model being used is linear. Regards, Vivek |
Title: Re: relation between group delay variation and horizontal eye closure Post by love_analog on Apr 7th, 2010, 2:05pm eye closure would occur because of ISI (ie Bandwidth limitation). It might be you are getting group delay variation due to some other factors (other than BW limitation). |
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