Re: [SI-LIST] : Re:

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From: Scott McMorrow (scott@vasthorizons.com)
Date: Wed Jun 21 2000 - 14:47:26 PDT


Roger and all,

One can, however, model the guard trace as a signal trace and treat
the "stitching vias" as extremely low resistance connections to a perfect
ground. The field solution for a guard trace and a signal trace is identical
for each coupled section between the stitch vias.

regards,

scott

--
Scott McMorrow
Principal Engineer
SiQual, Signal Quality Engineering
18735 SW Boones Ferry Road
Tualatin, OR  97062-3090
(503) 885-1231
http://www.siqual.com

"Rees, Roger R" wrote:

> Don't forget that xfx treats the guard trace as an IDEAL ground and > therefore is inaccurate. The field solution does not understand the > "stitching vias" that are used to connect the guard trace to the main > reference plane(s). > > Roger Rees > Intel Corp. > > -----Original Message----- > From: Charles Grasso [mailto:chasgra@email.msn.com] > Sent: Tuesday, June 20, 2000 11:31 PM > To: bkemp@lexmark.com; si-list@silab.eng.sun.com > Subject: [SI-LIST] : Re: > > Please explain "work". Does this mean lower crosstalk lower EMI?? > ----- Original Message ----- > From: <bkemp@lexmark.com> > To: <si-list@silab.eng.sun.com> > Sent: Tuesday, June 20, 2000 9:03 AM > > > I have gotten numbers using xfx that indicate guard traces do work. More > > importantly, I have seen positive effects on real boards. It is not > important > > to via to ground every "X" intervals of distance. It is critical that the > > "guard traces" are grounded at the source and receiver. It is also > necessary > > for the guard traces to via whenever the signal does. For instance, if > you have > > a clock trace that vias from layer 1 to layer 4 and is routed as > > ground-signal-ground (GSG), the ground (guard) trace should via from layer > 1 to > > layer 4 very closely. > > > > > > See below for some quick results. Compare numbers in bold for effects on > > crosstalk. > > > > Brandon Kemp > > EMC/SI Engineer > > Lexmark International, Inc. > > > > > > > > Trace width = 6 mils > > Edge to edge separation = 6 mils > > Height above ground plane = 7 mils > > Er = 4.5 > > > > 1. > > S S > > ___ ___ > > ___________________________GP > > Signals separated by 6 mil > > > > > > Configuration Name: SS_GP_7mil Conductors: 2 > > #INTEGRAL solution# > > Conductor index: 0 name: $$GND$$ > > Conductor index: 1 name: 1 > > Conductor index: 2 name: 2 > > > > i j Lij Cij Ze Zo Se So Fwdx Rvsx > > from to (nh/in) (pf/in) (ohms) (ohms) (ns/ft)(ns/ft) (s/s) (v/v) > > -------------------------------------------------------------------------- > > 1 1 9.791 2.176 68.57 - 1.71 - - - > > 1 2 2.735 0.334 82.47 53.02 1.82 1.60 0.132 0.217 > > 2 2 9.791 2.176 68.56 - 1.71 - - - > > ; > > > > > > 2. > > S S > > ___ ___ > > _____________________________GP > > Signals separated by 18 mil > > > > > > > > Configuration Name: S_S_GP_7mil Conductors: 2 > > #INTEGRAL solution# > > Conductor index: 0 name: $$GND$$ > > Conductor index: 1 name: 1 > > Conductor index: 2 name: 2 > > > > i j Lij Cij Ze Zo Se So Fwdx Rvsx > > from to (nh/in) (pf/in) (ohms) (ohms) (ns/ft)(ns/ft) (s/s) (v/v) > > -------------------------------------------------------------------------- > > 1 1 9.842 2.117 68.27 - 1.73 - - - > > 1 2 0.928 0.061 72.37 63.97 1.79 1.67 0.066 0.062 > > 2 2 9.842 2.117 68.28 - 1.73 - - - > > ; > > > > > > 3. > > G S G S > > ___ ___ ___ ___ > > _____________________________GP > > Signals separated by 18 mils, one trace routed GSG > > > > > > Configuration Name: GSGS_GP_7mil Conductors: 2 > > #INTEGRAL solution# > > Conductor index: 0 name: $$GND$$ > > Conductor index: 1 name: 1 > > Conductor index: 2 name: 2 > > XFX V6.5.0 Report 16 Jun 13:55 2000 Setup File = > > F:\bkemp\xfx\Scarecrow\Clocks\clks.xfx > > > > > > i j Lij Cij Ze Zo Se So Fwdx Rvsx > > from to (nh/in) (pf/in) (ohms) (ohms) (ns/ft)(ns/ft) (s/s) (v/v) > > -------------------------------------------------------------------------- > > 1 1 8.206 2.253 60.35 - 1.63 - - - > > 1 2 0.237 0.022 61.51 59.18 1.65 1.62 0.019 0.019 > > 2 2 8.928 2.184 63.94 - 1.68 - - - > > ; > > > > > > .xfx > > CONFIG SS_GP_7mil e: 1.00 > > INTEGRAL > > DIELECTRIC e: 4.50 HORIZ_PLANE y: 0.0 7.0 > > CONDUCTOR 1 RECTANGLE x: 0.0 6.0 y: 7.0 9.0 > > CONDUCTOR 2 RECTANGLE x: 12.0 18.0 y: 7.0 9.0 > > GROUND HORIZ_PLANE y: -1.5 0.0; > > > > CONFIG S_S_GP_7mil e: 1.00 > > INTEGRAL > > DIELECTRIC e: 4.50 HORIZ_PLANE y: 0.0 7.0 > > CONDUCTOR 1 RECTANGLE x: 0.0 6.0 y: 7.0 9.0 > > CONDUCTOR 2 RECTANGLE x: 24.0 30.0 y: 7.0 9.0 > > GROUND HORIZ_PLANE y: -1.5 0.0 > > ; > > > > CONFIG GSGS_GP_7mil e: 1.00 > > INTEGRAL > > DIELECTRIC e: 4.50 HORIZ_PLANE y: 0.0 7.0 > > GROUND RECTANGLE x: -12.0 -6.0 y: 7.0 9.0 > > CONDUCTOR 1 RECTANGLE x: 0.0 6.0 y: 7.0 9.0 > > GROUND RECTANGLE x: 12.0 18.0 y: 7.0 9.0 > > CONDUCTOR 2 RECTANGLE x: 24.0 30.0 y: 7.0 9.0 > > GROUND HORIZ_PLANE y: -1.5 0.0 > > ; > > > > > > > > **** To unsubscribe from si-list or si-list-digest: send e-mail to > > majordomo@silab.eng.sun.com. 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