[SI-LIST] Re: Routing differential lines as single ended traces ?
- From: Danny Damhave <dd@xxxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Mon, 26 Sep 2011 21:24:56 +0200
Hi,
Routing a LVDS differential pair with a tightly coupling, is sensitive to
production tolerances/variation eg. etching factor/coating.
Having a weak coupling or using the not closer than rule (single ended traces)
is less sensitive.
If your traces are wide and your timing is very critical is probably best to
route with a very weak or weak coupling and match the trace to trace spacing
with the pitch of the glass fibres in your laminate to reduce the skew between
the signals, but of course this can also be achieved by staying away from 90deg
routing and using the not closer rule.
I assume that your signals always have a reference plane, are not close to any
edge of the PCB, do not leave the board , and are not close to noise sources
like DC DC switchers and your signals are not influenced by PCB resonances or
the like.
BR
Danny Damhave
On 26/09/2011, at 03.57, Low Jerry wrote:
> Hi,
> I recently came across a validation platform where the LVDS differential
> lines are routed as single ended traces traces instead of tightly coupled
> differential pairs. The motivation I found was so that they could use each
> of the pairs as single ended traces when needed as well. When I probed
> deeper it seems like the person who proposed this scheme has left. So I
> would like to seek help here on some clarification
>
> - Will a scheme like this impact the performance of the differential pair
> ? Since I understand that differential routing is more immune to noise.
> - What are the considerations/feasiblity studies that need to be done
> before implementing a scheme like this ?
> - Since this is a validation platform what measures can be taken ensure
> that the performance seen are similar to a production platform if the
> production platform is routed in differential.
>
> Thanks in advance for the feedbacks. Have a great day.
>
>
> ------------------------------------------------------------------
> 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 technical documents are available at:
> http://www.si-list.net
>
> 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
>
>
------------------------------------------------------------------
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 technical documents are available at:
http://www.si-list.net
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
Other related posts:
