RE: [SI-LIST] : Re:

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From: Rees, Roger R (roger.r.rees@intel.com)
Date: Wed Jun 21 2000 - 07:35:03 PDT


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
> ;
>
>
>
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