FreeLists / si-list / [SI-LIST] Re: Resistor packs, SI issues?

["Dunbar, Tony" <tony_dunbar@xxxxxxxxxx>]

Hello,

This is an interesting topic and one I've been curious about for a while
so this little refresher prompts me to pitch in. Has anyone done any
studies and simulations on crosstalk for such resistor packs? Actually,
does anyone have the models to facilitate that?

Thanks!
Tony

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Anders Frederiksen
Sent: Tuesday, November 15, 2005 8:47 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Resistor packs, SI issues?

Hello All,

I've encountered a constraint on the signal allocation in resistor
packs. The application is a DDR-I interface. Frankly I was quite puzzled
to see that Intel specifically prohibit routing DQS (strobes) and other
(ie. data mask) signal in one respack!
If it weren't for the notes I'd never blink mixing <200MHz signals in
respacks. I'm using 0804 packs and fail to realize that cross talk could
be a big problem here? Of course the signals are raised from the
reference plane and the horizontal spacing between the signals is, say,
double up for discrete resistors (or separate packs).
Is it the base material used in the packs that cause "issues"? Or am I
completely missing something??? I haven't been able to find any
investigations regarding use of respacks - so I'm very interested in
hearing about your experiences/opinions!

Cheers,
 Anders

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