[SI-LIST] AW: Re: Reduction of crosstalk by using stitching vias between traces
- From: "Havermann, Gert" <Gert.Havermann@xxxxxxxxxxx>
- To: "Pehr Andersson" <andersson.pehr@xxxxxxxxx>, "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>, "Rick Brooks (ricbrook)" <ricbrook@xxxxxxxxx>
- Date: Thu, 5 Jan 2012 13:49:35 +0000
Pelle,
the effect is minimal. I'd guess, that you will reduce the x-talk of the
microstrip by 2%, and the stripline by 1% (attention: I'm talking about total
reduction. I'm not saying stitching brings you down to 1% x-talk!!!).
Just for reference, 4 mil of additional separation between the differential
pairs gives you approx, 5-10dB lower crosstalk (5dB microstrip, 10dB stripline
depending on the topology). Having a separation of >3x the tracewidth in
stripline already gives you approx 30dB isolation (2% x-talk).
Distance is much more effective for isolation than stitching vias.
BR
Gert
----------------------------------------
Absender ist HARTING Electronics GmbH & Co. KG; Sitz der Gesellschaft:
Espelkamp; Registergericht: Bad Oeynhausen; Register-Nr.: HRA 5596; persönlich
haftende Gesellschafterin: HARTING Electronics Management GmbH; Sitz der
Komplementär-GmbH: Espelkamp; Registergericht der Komplementär-GmbH: Bad
Oeynhausen; Register-Nr. der Komplementär-GmbH: HRB 8808; Geschäftsführer:
Edgar-Peter Duening, Torsten Ratzmann, Dr. Alexander Rost
-----Ursprüngliche Nachricht-----
Von: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] Im
Auftrag von Pehr Andersson
Gesendet: Donnerstag, 5. Januar 2012 13:37
An: si-list@xxxxxxxxxxxxx; Rick Brooks (ricbrook)
Betreff: [SI-LIST] Re: Reduction of crosstalk by using stitching vias between
traces
Thanks for the presentation Hany and thanks for your comments Rick.
I have 4 inches of microstrip- and stripline traces that are running at
10Gbit/s.
In this particular case where I want to reduce the crosstalk, it is between two
traces, where one trace is RX and other one is TX.
How much reduction in crosstalk could I expect if I stitch the gap between two
differential traces, with 20 thru hole stitiching vias, drill hole diameter of
10 mils?
This is both for microstrip and stripline trace.
Diff impedance is 100 Ohms.
Are there any disadvantages from the SI/PI perspective in using stitching vias
between traces?
Thanks! /Pelle
2012/1/4, Rick Brooks (ricbrook) <ricbrook@xxxxxxxxx>:
> I suppose it depends on other things too:
> stripline, microstrip, or other?
> GND stitching via type and size: thru hole or micro via?
> diff pair impedance?
> required isolation between pairs, in dB?
>
> From my experience, a gap between the 100 ohm pairs gives you what you
> need for typical driver edge rates, adding GND stitching vias in that
> same gap does not make it much better.
> If you could use very small microvias from GND plane to GND plane,
> that could be much better, I do not know.
>
> thanks,
> - Rick
>
>
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Pehr Andersson
> Sent: Wednesday, January 04, 2012 11:43 AM
> To: si-list@xxxxxxxxxxxxx; si-list-bounce@xxxxxxxxxxxxx
> Subject: [SI-LIST] Reduction of crosstalk by using stitching vias
> between traces
>
> Hello dear readers!
>
> How efficient are stitching vias for reducing crosstalk (FEXT & NEXT)
> between pairs of differential traces?
>
> Lets say you have 5/6/5 mils traces that are separated 30 mils from
> another 5/6/5 trace, both traces are running at 10 Gbit/s.
>
> Best regards, Pelle
> ------------------------------------------------------------------
> 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
------------------------------------------------------------------
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:
