[SI-LIST] Re: Ground problems
- From: "Jon Powell" <jonpowell@xxxxxxxxxxxx>
- To: <jlevieux@xxxxxxxxxxxxxxxxxx>, <stephanie.goedecke@xxxxxxxxxxx>,<raman@xxxxxxxxxxxxx>
- Date: Fri, 30 May 2003 09:02:32 -0700
Perhaps if you gave a little more info on your objective people would chime
in with more help. For instance:
1) What are you trying to achieve? DC connection, HF connection, or both?
2) Why aren't these planes connected directly with metal fills?
3) Are the planes capacitvely coupled (if not, why not)
The problem I think that others are alluding to is that any descrete
connection carries with it parameters that are not in the spec (ie. a 0ohm
resistor has some R C and L inherent in the connection and there is also
perhaps a large amount of L inherent in the path used for the connection.
regards,
jon
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of John LeVieux
Sent: Friday, May 30, 2003 8:51 AM
To: 'stephanie.goedecke@xxxxxxxxxxx'; 'raman@xxxxxxxxxxxxx'
Cc: 'si-list@xxxxxxxxxxxxx'
Subject: [SI-LIST] Re: Ground problems
Stephanie,
What is the difference between the 0 ohm resistor and the wire? Have you
found 0 ohm resistors that do not measure to be 0 ohms? I am working on a
design that has a separated analog and digital ground area that needs to be
connected in the same manner as Ramana described and I would like to
understand the issue with the 0 ohm resistor.
Thanks,
John LeVieux
Littlefeet
Poway, CA
-----Original Message-----
From: stephanie.goedecke@xxxxxxxxxxx
[mailto:stephanie.goedecke@xxxxxxxxxxx]
Sent: Wednesday, May 28, 2003 12:23 AM
To: raman@xxxxxxxxxxxxx
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Ground problems
Hi Ramana,
I think it might not be a 0 Ohm resistor. Would you consider replacing it
with
a wire, and repeating the measurement?
regards,
Stephanie
Stephanie Goedecke
Philips - SP3D Chip Design GmbH
Petersbrunnerstr.17
82319 Starnberg / Germany
Phone: +49-8151-270-160
Fax : +49-8151-270-200
To:
<si-list@xxxxxxxxxxxxx>
cc: (bcc: Stephanie
Goedecke/STN/SC/PHILIPS)
Subject: [SI-LIST]
Ground problems
"Ramana Rao Rayudu" Classification:
<raman@xxxxxxxxxxxxx>
Sent by:
si-list-bounce@freelists
.org
2003-05-27 01:45 PM
Please respond to raman
Hello,
We are testing the power supply (VRM 8.5 compatible) for our processor
board.
We have a split ground - the power supply ground and the digital ground
shorted at one single point with a 0 ohm resistor. There is no signals
crossing over and I do not think there are any loops.
The voltage difference between the 2 grounds is very large. The CRO shows
a p-p of 2V when measuring between the 0 ohm resistor.
What could be the reason for this and what could the remedies.
Thanks and Regards
Ramana Rao Rayudu
Real Time Systems Group
Centre For Development Of Advanced Computing
No.1 Old Madras Road, Byappanahalli
Bangalore - 38, India
Ph 91-80-5244059
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