[SI-LIST] Re: One stitching via or more vias is better for 25Gbps application???

  • From: "Hany Fahmy" <hanymhfahmy@xxxxxxxxxxxxxxxxxxx>
  • To: <buenos@xxxxxxxxxxx>, <leeritchey@xxxxxxxxxxxxx>, <lee.home.61@xxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
  • Date: Sat, 6 Sep 2014 23:03:28 +0200

It is a fact that real-silicon drivers of these signals r injecting
common-mode propagation, therefore, the GND stitching becomes a critical &
integral part for the modes of propagation along w the diff-modes of
propagation. 
Hany Fahmy 
Intelligent Solutions BVBA
                  
hanymhfahmy@xxxxxxxxxxxxxxxxxxx
http://www.intelligentsolutionsbvba.com/
http://www.linkedin.com/pub/hany-fahmy/66/852/b11
Phone: +32471650724


-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Istvan Nagy
Sent: Saturday, September 6, 2014 10:52 PM
To: leeritchey@xxxxxxxxxxxxx; lee.home.61@xxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: One stitching via or more vias is better for 25Gbps
application???

Lee,

Did you do simulations both with/without stitching vias?
Also try the simulation on a diffpair that previously (before arriving to
the via) got some skew/imbalance. I don't know but suspect that the skewed
diffpair will get more mode transformation if the return paths are not good.

To be tested with simulation. It was a lot of work for us to set the signal
via to gnd via distance to minimize reflections. Now with no gnd via, the
signalvia to gnd via distance depends on the surrounding elements in the pcb
layout.
How about via impedance and reflections? Without the stitching vias, the
signal via impedance will be as much as "who knows".

Regards,
Istvan Nagy


-----Original Message-----
From: Lee
Sent: Saturday, September 06, 2014 12:17 PM
To: lee.home.61@xxxxxxxxx ; si-list@xxxxxxxxxxxxx
Cc: lee.home.61@xxxxxxxxx
Subject: [SI-LIST] Re: One stitching via or more vias is better for 25Gbps
application???

No stitching vias are needed.  Where did this idea get started?

-----Original Message-----
From: Leeyuyun
Sent: Saturday, September 06, 2014 4:25 AM
To: si-list@xxxxxxxxxxxxx
Cc: lee.home.61@xxxxxxxxx
Subject: [SI-LIST] One stitching via or more vias is better for 25Gbps
application???

Hi, all
I am doing 100Gbps (4x25Gps) product now How do we put stitching vias when
high speed signal change the layer?
This is a differential pair, which has P and N Someone told me that one
stitching vias is better because P and N share the common return Someone
told me that more stitching vias is better because loop inductance could be
reduced more I am confused which one is better?
Can anyone help me?
Thanks,
Lee------------------------------------------------------------------
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:
http://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:
http://www.freelists.org/archives/si-list

Old (prior to June 6, 2001) list archives are viewable at:
  http://www.qsl.net/wb6tpu




-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2014.0.4765 / Virus Database: 4015/8162 - Release Date: 09/05/14

------------------------------------------------------------------
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:
http://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:
http://www.freelists.org/archives/si-list

Old (prior to June 6, 2001) list archives are viewable at:
  http://www.qsl.net/wb6tpu



---
This email is free from viruses and malware because avast! Antivirus
protection is active.
http://www.avast.com

------------------------------------------------------------------
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:
http://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:     
                http://www.freelists.org/archives/si-list
 
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu
  



------------------------------------------------------------------
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:
http://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:     
                http://www.freelists.org/archives/si-list
 
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu
  

Other related posts: