[SI-LIST] Re: WHich dielectric to use
- From: Bert Simonovich <bertsimonovich@xxxxxxxxxx>
- To: "avtaarenator@xxxxxxxxx" <avtaarenator@xxxxxxxxx>
- Date: Sun, 2 Sep 2012 23:17:45 -0400
Avtaar,
There could be many reasons why the channel is not working. The first thing I
would check is for via stubs, particularly on the backplane connector
footprint. Eg. - If your backplane is thick and has many layers then routing
high speed signals near the surface where the connector is and not backdrilling
the remaining stub could be devastating to the eye opening due to 1/4 wave
resonant freq. If you know the stub length in inches, then Res freq (fo) can
be estimated by:
fo=1.18E10/(4*stub_len*sqrt(er))
Next would be checking the layout for Xtalk and how well the diff pairs are
routed for intra-pair skew from chip to chip.
Finally pre-emphasis and receive equalization settings on silicon should be set
accordingly.
BR//
Bert Simonovich
On 2012-09-02, at 9:33 PM, Avtaar Singh <avtaarenator@xxxxxxxxx> wrote:
> I have to design a telecom system to run at 20 Gbps.
> I tried the following:
>
> 1. FR4 on backplane and daughtercards - did not work
> 2. Nelco4K-13EP on backplane and daughtercards - did not work
>
> I was just wondering which of these next steps could give me
> the desirable results? Is this sequence mentioned below close to what I
> should be trying for iterative link level simulations
>
> 1. Megtron 6 on backplane & Nelco4K-13EP on daughtercards?
> 2. Megtron 6 on backplane & Nelco4K-13EPSI on daughtercards?
> 3. Megtron 4 on backplane & Nelco4K-13EP on daughtercards?
> 4. Megtron 4 on backplane & Nelco4K-13EPSI on daughtercards?
> 5. Megtron 6 on backplane as well as daughtercards?
> 6. Megtron 4 on backplane as well as daughetrcards?
>
>
> -------
>
> Regards,
> Avtaar Singh
>
>
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