Hi Gilles: I'm on both sides on this issue. This is one of the best examples of why you should never do anything by rote rule. Over the years I have split many planes without ever having a problem. To be fair I have also closed splits too. I don't have problems because I analyze every occurrence. You need to understand what is meant by a return image in a plane and ground return paths. Often when I am working with someone I will make paper plots of my traces and have the other person take a pencil and trace the return paths for all high frequency and all high current circuits. If that path has a lot of detours I know something is wrong. I also look at the current loops. If there is a lot of area within the loop, something is wrong. The Analog Devices pages you refer to are good references. They offer good solutions to difficult problems but again, don't do anything because they tell you to. Understand the problem and you will be able to make the correct tradeoffs. As for where to get the basic knowledge, the SI achieves are full of book reference. Many times the authors of those books are here to answer specific questions but they can't do it in a general posting here. Fred Townsend -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Gilles Aminot Sent: Friday, September 21, 2007 2:09 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Need technical ammunition for switching to single ground plane ! Hi Everyone, =20 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:=20 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.. =20 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. =20 Kindest Regards, Gilles Aminot, P.Eng Hardware Design Engineer =20 Librestream Technologies Inc Unit 200 - 55 Rothwell Rd Winnipeg MB. Canada R3P-2M5 PH: 204-487-0612 Ext 218 FX: 204-487-0914 =20 =20 ------------------------------------------------------------------ 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 technical documents are available at: http://www.si-list.net List archives are viewable at: =20 //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 =20 ------------------------------------------------------------------ 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 technical documents are available at: http://www.si-list.net 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