[SI-LIST] Re: guard traces (huge)
- From: "Moshe Frid" <moshef@xxxxxxxxxxx>
- To: "'Istvan NOVAK'" <istvan.novak@xxxxxxxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Sun, 18 Jul 2004 19:19:05 +0200
Thnks.
What about filling the traces layer whit plane stitched to the ground plane
do you recommend to do it, And whit what space.
-----Original Message-----
From: Istvan NOVAK [mailto:istvan.novak@xxxxxxxxxxxxxxxx]
Sent: Sunday, July 18, 2004 5:06 PM
To: moshef@xxxxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: Re: [SI-LIST] guard traces (huge)
Moshe,
As this topic came up in the past on this list, you can also search the
archives for previous comments.
My brief summary is this: guard traces work like lightning rods, by
attracting stray field that otherwise would end up on victim lines, creating
crosstalk. A guard trace with width similar to that of regular traces will
give an additional 6-15 dB isolation (base line: crosstalk between two lines
with a fixed spacing, guard trace not present). Note that in microstrip far
field, crosstalk drops quadratically with spacing. In stripline, crosstalk
drops with the fourth power of spacing, so it is always prudent to spread
traces first as much as room permits. In wide digital buses, guard traces
between all adjacent trace combinations is not very practical, mostly
because you also need a sufficient number of vias stitching the guard traces
to ground to break up the resonators created by the grounded-ended guard
traces. The minimum stitching distance should be less than the wavelength
at the bandwidth of signals.
Guard traces may be effective protecting a few sensitive lines, mostly in
mixed analog-digital systems. Buffered guared traces can also reduce the
impact of surface conduction and stray capacitance in instrumentation
amplifiers.
Best regards,
Istvan Novak
SUN Microsystems
----- Original Message -----
From: "Moshe Frid" <moshef@xxxxxxxxxxx>
To: <si-list@xxxxxxxxxxxxx>
Sent: Sunday, July 18, 2004 11:26 AM
Subject: [SI-LIST] guard traces (huge)
> Hi All
> can someone tell me something about rules of guard trace
> what space need to be kept
> do they have to be connected to the ground plane and how do they affect
> the impedance of the trace that is guarded ?
>
>
> Moshe Frid
> Adcom pcb design
>
> Mobile :066-573232
>
> Tel. 972-9-7417411 (108)
>
> Email:moshef@xxxxxxxxxxx
>
>
>
> ------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
> or to administer your membership from a web page, go to:
> //www.freelists.org/webpage/si-list
>
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
> List FAQ wiki page is located at:
> http://si-list.org/wiki/wiki.pl?Si-List_FAQ
>
> List technical documents are available at:
> http://www.si-list.org
>
> List archives are viewable at:
> //www.freelists.org/archives/si-list
> or at our remote archives:
> http://groups.yahoo.com/group/si-list/messages
> Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu
>
>
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
