Huh? You cannot have "impedance matched" differential vias without ground
stitching vias. Sorry. That is the physics of vias in printed circuit boards.
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-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On ;
Behalf Of Julia Nekrylova
Sent: Friday, December 9, 2016 12:39 PM
To: dmarc-noreply@xxxxxxxxxxxxx
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: XTalk power flow in differential vias
There might be no room for stitching vias if they are the same size as
differential vias which are impedance matched. But you can make them smaller,
especially on those 42 mil thick optical boards.
08 Дек 2016 г. 21:33 пользователь "Vinu Arumugham" <
dmarc-noreply@xxxxxxxxxxxxx> написал:
Lee,
"There is no room for "stitching vias'"
There is no free lunch either.
Without stitching vias, interconnect common mode return loss goes up.
Since neither TX nor RX has a perfect common mode termination, common
mode signals will keep reflecting until they are converted into
differential or radiated.
So you pay for it with lower margins or more expensive shielding measures.
Thanks,
Vinu
On 12/07/2016 05:25 PM, heyfitch (Redacted sender heyfitch for DMARC)
wrote:
You are free to design your own test board to convince yourself oneor another. Right?
way
- VadimÂleeritchey@xxxxxxxxxxxxx> wrote:
On Wednesday, December 7, 2016, 17:01, leeritchey <
no room for "stitching vias'. Â These all work very well. Â You will
Cadin, I do design with hundeds of channels densely packed. Â There
is
find this the norm with big iron.
Maybe stitching vias are over kill. To use them I would have to bethat their effect is significant rather than just visible .
shown
Original message --------
Sent via the Samsung Galaxy S® 6, an AT&T 4G LTE smartphone--------
From: heyfitch <heyfitch@xxxxxxxxx>si-list@xxxxxxxxxxxxx
Date: 12/06/2016 8:36 PM (GMT-08:00)
To: leeritchey@xxxxxxxxxxxxx, shlepnev@xxxxxxxxxxxxx,
Subject: Re: [SI-LIST] Re: XTalk power flow in differential vias#715FFA solid !important;padding-left:1ex
blockquote, div.yahoo_quoted {margin-left:0
!important;border-left:1px
!important;background-color:white;}Lee,In
fiber optics modules, for example, the density is so high that diff
vias are often right next to one another. Â The natural inclination is
to have as few stitching vias as possible - to have more routing
channels. Â So, 2 stitching vias per a diff via is typical. Â Yuriy's
video clearly shows how the lower number of stitching vias result into
higher insertion loss. Â This is a trade off consideration, imho.Â
Also, it is desired to have less than 40dB crosstalk between channels.
That is another consideration.Â
Regards,Vadim Heyfitchleeritchey@xxxxxxxxxxxxx> wrote:
On Monday, December 5, 2016, 13:49, Lee Ritchey <
On
Why are we worrying about differential vias?
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]
Behalf Of Yuriy ShlepnevScreenCasts.php
Sent: Monday, December 5, 2016 11:58 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] XTalk power flow in differential vias
Hello Everyone,
Last Friday I have uploaded visualization of crosstalk power flow in
differential vias - see #2016_13 at http://www.simberian.com/
appreciate
 -> How Interconnects Work (higher quality, but may be slow),
YouTube version is available at https://youtu.be/IyuQIl8T_uE The ;
demo video illustrates two ways for the crosstalk reduction. I was
really fascinated with the power flow view of the crosstalk :-) As
always, I will
any feedback.Finalist
Best regards,
Yuriy
Yuriy Shlepnev, Ph.D.
President, Simberian Inc.
2629 Townsgate Rd., Suite #235, Westlake Village, CA 91361, USA
Office
+1-702-876-2882; Fax +1-702-482-7903 Cell +1-206-409-2368; Virtual
+1-408-627-7706
Skype: shlepnev
www.simberian.com
Simbeor - Accurate, Productive and Cost-Effective Electromagnetic
Signal Integrity Software
2010 and 2011 DesignVision Award Winner, 2015 Best In Design&Test
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