[SI-LIST] Re: Best routing layer for SERDES
- From: hanymhfahmy@xxxxxxxxx
- To: marc-andre.filion@xxxxxxxxxxxxxx,mervin.jacob@xxxxxxxxxxx
- Date: Thu, 19 Apr 2012 21:09:59 +0000
Hi,
Concur that stripline n to be more specific: symmetric stripline w equal height
of prepreg n core is the best.
Concur also that via stubs is very painful for SERDES channels n therefore
backdrilling n also via parameter optimization using 3D EM tools such as MOM or
FEM is required to guarantee successful operation.
Special care of the PCB material w low loss-tangent is required for long
routing as long as 10-inches on such backplanes such as those w 14-slots trying
to hit 10Gbps per lane on such copper backplanes.
Then the final recipe is the optimization of the equalizers of Td n Rx is a
must for such high data rates.
Concur also that radiated emission is minimized w stripline routing as well.
If going to 25GBps then surface roughness model of TLs is required.
Wish u a successful design.
Hany Fahmy
Agilent Technologies.
Sent via BlackBerry offered by Mobinil
-----Original Message-----
From: "Filion, Marc-Andre" <marc-andre.filion@xxxxxxxxxxxxxx>
Sender: si-list-bounce@xxxxxxxxxxxxx
Date: Thu, 19 Apr 2012 16:54:00
To: <mervin.jacob@xxxxxxxxxxx>
Reply-To: marc-andre.filion@xxxxxxxxxxxxxx
Cc: <si-list@xxxxxxxxxxxxx>
Subject: [SI-LIST] Re: Best routing layer for SERDES
Hi,
I would say that stripline is better(for all reason mention earlier), but you
have to be careful with via stub. It can really be annoying. Microstrip routing
simplify this aspect.
If you can live with back-drilling, I definitely go with stripline.
Regards,
Marc-André Filion, Eng | Hardware designer | Kontron Canada | T 450 437 5682
x2243 | E marc-andre.filion@xxxxxxxxxxxxxx
Kontron Canada Inc
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-----Message d'origine-----
De : si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] De la
part de Mark Filipov
Envoyé : 19 avril 2012 16:11
À : mervin.jacob@xxxxxxxxxxx
Cc : si-list@xxxxxxxxxxxxx
Objet : [SI-LIST] Re: Best routing layer for SERDES
Stripline is usually used for high-speed signal transmission on backplanes and
boards with many layers.
Microstrips are more susceptible to EMI and there is also more mode conversion
with microstrips.
Also the FEXT limits how long traces you can use on microstrips.
2012/4/15, Dudi Tash <dudi@xxxxxxxxxxxxxxxxx>:
> Hi Mervin,
>
> Due to lack of additional info regarding the interface I'd suggest the
> following general guidelines:
>
> My preference would be Microstrip and the reasons for that:
>
> 1. In case possible and the SERDES signals are in the egde BGA balls,
> no need for vias, meaning no parasitic L and C on the traces, nor
> stubs (in case T.H vias are used).
> 2. Since SERDES signals are differential, the XTALK problems are
> considerably reduced 3. Skin effect wise - since the traces in
> Microstrip are plated, the final trace thickness shall be 1.5oz,
> meaning the cross section of the trace is wider, hence lower skin
> losses 4. If possible, rout the traces as wide as possible - again,
> lowering the skin effect problems.
> 5. I'd also make round differential pairs - very much similar to RF
> traces
>
> I hope this helps
>
> Best Regards,
> Dgtronix Ltd. I Founder & CEO I Dudi Tash
> eFax: +972-3-7256490 I Mobile: +972-54-6345629 I Office:
> +972-9-9660967 www.dgtronix-tech.com
>
>
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