[SI-LIST] Re: Need technical ammunition for switching to single ground plane !
- From: <Aubrey_Sparkman@xxxxxxxx>
- To: <gilles.aminot@xxxxxxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Mon, 24 Sep 2007 16:11:36 -0500
IMHO, the first step is to resolve the conflict between the two
statements: "I'm not pleased with our audio performance" and "It's good
enough" If you have a performance specification and it meets those
specifications, go have a beer! If you don't have a performance
specification, start there. =20
Aubrey Sparkman=20
Enterprise Engineering Signal Integrity Team=20
Dell, Inc.=20
Aubrey_Sparkman@xxxxxxxx=20
(512) 723-3592=20
"Discovery consists of seeing what everybody has seen and thinking what
nobody else has thought." - Jonathan Swift
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Gilles Aminot
Sent: Monday, September 24, 2007 3:32 PM
To: Gilles Aminot; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Need technical ammunition for switching to single
ground plane !
I'd like to thank everyone for their responses! I guess one thing I
stated incorrectly was that I'm "working on a new design", a better
description is "new version of existing design". I'm not pleased with
our audio performance but the current thinking is that "it's good
enough, so why should we change to solid plane if split plane is
working"! It's almost impossible to argue against such a comment,
perhaps I should just let it go, call it a day and have a beer!
I was really hoping to see a case study which would allow me to convince
my peers that single plane would not cause more problems and may
actually help improve things. I guess this single vs split plane "case
study or technical paper" doesn't exist. Perhaps it's too much to ask
given that there are so many variables which can affect noise.
To answer Lee's famous 5 questions.
> > > > 1. Is there a problem that needs to be solved?=3D20
Yes, but no one else acknowledges there is a problem today (experience
tells me it will come back to haunt me, or bite me in the you know what)
> > > > 2. What, exactly is the problem?=3D20
Too much noise in the audio but only 1 pass of new PCB allowed.
=3D20
> > > > 3. Does the proposed "single ground plane" solution solve the
problem (compared to split plane we have today)?
I don't know and I don't know how to calculate or figure this out? I
wish someone could help me figure this out through analysis and not
board spins.
> > > > 4. Does the proposed solution not create any new problems?
I don't think so, but again I don't know and I'm not sure how to figure
it out? I wish someone could help me figure this out through analysis
and not board spins.
> > > > 5. Is there no better solution than current "split plane" which
is working "good enough"?
Maybe single plane is better? But I need 'proof' because it's perceived
as a higher risk than "leave as is".
After anwering those questions I still can't prove that "leave as is"
split planes approach with new new layout won't create new problems
either (question #4) Arghh.
Is it too early for that beer!=3D20
Regards,
Gilles
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Gilles Aminot
Sent: Friday, September 21, 2007 4:09 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Need technical ammunition for switching to single
ground plane !
Hi Everyone,
=3D20
I'm working on a new design and would like to eliminate split ground
planes. In the past we've always split the analog ground plane (for
analog audio circuits and codecs) and joined it at one location
(sometimes shorting or through an inductor). I've read lot's of postings
on this group explaining good reasons not to split ground planes, but
the only real supporting documentation I have seen is the following
article:=3D20
http://www.analog.com/analog_root/static/pdf/raq/RAQ_groundingADCs.pdf
<http://www.analog.com/analog_root/static/pdf/raq/RAQ_groundingADCs.pdf>
and it does not provide much depth..
=3D20
I have been meeting some resistance to eliminating the split ground
planes and I am looking for technical articles showing the advantages of
using a single ground plane in designs with mixed high speed digital and
sensitve analog circuits. I keep bumping my head against datasheets or
articles that say analog & digital grounds should be separated (such as:
http://www.ultracad.com/articles/planesplits.pdf), which makes it
difficult to convince my peers that changing our approach is the way to
go. Can anyone share or point me to articles which may help me plead my
case. I would also appreciate if anyone could share some real life
experiences of going from split to single ground plane.
=3D20
Kindest Regards,
Gilles Aminot, P.Eng
Hardware Design Engineer
=3D20
Librestream Technologies Inc
Unit 200 - 55 Rothwell Rd
Winnipeg MB. Canada
R3P-2M5
PH: 204-487-0612 Ext 218
FX: 204-487-0914
=3D20
=3D20
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