re: [SI-LIST] : crosstalk through resistor networks?

fabrizio zanella (fabrizio=zanella%eng%emchop1@fishbowl02.lss.emc.com)
Mon, 17 Aug 98 13:18:53 -0400

Andrew, great timing on your question!
I was just measuring crosstalk last week on a driver board plugged into a
backplane with terminator boards on the back side. The terminator boards
have CMD resistor packs (GTL+ pull up terminations), the input signal is
GTL+, 1ns rise/fall time, 8 data lines switching, all terminated in same
resistor pack. I measured the crosstalk attributable to the QSOP resistor
packs to be ~ 2.5%, or 25mV peak to peak.
Hope this helps,
Regards,
Fabrizio Zanella
EMC
fzanella@emc.com
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Original Text
From: "Andrew Phillips" <andrew@scs.ch>, on 8/14/98 9:07 AM:
To: smtp@Eng@EMCHOP1["SI-LIST" <si-list@silab.Eng.Sun.COM>]

Hello,

I am interested in using some small-package (QSOP) resistor networks for
terminating a large number of bus-signals in a design. Signal rise-times
range from ~200ps to 1ns or so.

I have found some devices that look suitable here:
http://www.bourns.com/cat/MNETXX1.htm

I am wondering whether such an approach will have crosstalk problems.
Has anyone analysed this and can give me some advice?

I presume that if traces are suitably separated before and after the
resistor package then the crosstalk induced between adjacent signals
will be reduced. These signals are very close together for the 3mm or so
across the resistor package - is this likely to cause problems?

Thanks for any help,

Andrew Phillips
Supercomputing Systems AG
Zurich, Switzerland

Need 'C6x DSP info?
http://www.scs.ch/~andrew/c6x.html
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