Hi,
Fiber weave effect might split to 2 effects with 100G-PAM4.
Typically we talked about "fiber weave effect" to describe accumulated skew
at the end of the diffpair, due to trace to fiber weave parallelism. In some
articles I read about angled routing (or rotated boards) when crossing he
weaves at low angles creating impedance weaviness on the TDR, and they
mentioned that this creates suck-outs above 30GHz, if I remember correctly.
This is a second "fiber weave effect". To differentiate, we would call the
first one as "fiber weave skew effect" FWSE, and the new one as "fiber weave
crossing effect" FWCE. From measurements and research done, we know that we
can significantly minimize FWSE by rotating at minimum 6 degrees or more.
But, what minimum or maximum rotations are needed for minimizing FWCE ?
Also, how bad is FWCE ? Maybe we need to do measurements again (different
angles, different glass styles) on a trace near the maximum of the loss
budget, note the suck-out depth and frequency, whether it crosses the IEEE
annex69B thresholds.
With 56G-PAM4, I didn't see FWCE interfering with anything, as the nyquist
was still 13GHz, wile this effect is predicted to be around more than twice
as much.
Did anyone do some more research or measurements on this?
Regards,
Istvan Nagy
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
