[SI-LIST] Re: stripline return paths etc.
- From: steve weir <weirsp@xxxxxxxxxx>
- To: lalexman@xxxxxx, <si-list@xxxxxxxxxxxxx>
- Date: Mon, 06 Dec 2004 09:16:11 -0800
Leonard, what you have with all the plane breaks is much more like a buried
microstrip. The signal layer closer to the solid plane will exhibit higher
impedance than a true stripline, and some modulation along the frequency
axis. The signal layer closer to the split planes could look like a mess
depending on several factors. You should avoid placing signals with high
edge rates close to those splits. If you must run signals across the
splits then bypass the splits with capacitors.
It is all in the inductance. If you have a high inductance loop, between
the two grounds, then you are setting yourself up for a lot of
trouble. You really need to ask yourself, or whoever came up with this
scheme what it is they are trying to do, and why those grounds need to be
single pointed. You really ought to consider getting some expert help.
Steve
At 07:55 AM 12/6/2004 -0800, Leonard Alexman wrote:
>Hi All,
>I am designing many pcb's with multiple power and ground planes and I was
>curious if some has an opinion or could point me to any articles on the
>following questions.
>
>
>1. I know its best to have a sold ground plane (or solid power plane )
>on either side of the a stripline trace but is it acceptable to have a solid
>ground plane on one side and a power plane on the other side with many
>splits in the plane ? The same question for a dual stripline configuration
>?
>
>2. I have some high speed differential signals that have a separate
>ground (HSGND). HSGND is tied to digital ground thru a zero ohm resistor. I
>am routing these signals in a stripline configuration with HSGND planes on
>either side. Can I also route digital signals(that use the digital ground )
>on this layer ? I am concerned that the return path goes thru the zero ohm
>resistor to the digital ground plane. and it will be a very long return
>path. Is my assumption correct ?
>
>
>Thanks for any help
>
>Leonard Alexman / American Electronics Group Inc.
>PH: 951-354-6493
>Cell: 951-640-5469
>Fax: 208-247-33470
>
>
>
>-- Binary/unsupported file stripped by Ecartis --
>-- Type: application/ms-tnef
>-- File: winmail.dat
>
>
>------------------------------------------------------------------
>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:
