Zhengrong, The image or return current will eventually get back to the buffer but may take not take a single reference plane to get back. It all depends on your stack-up and how you routed your buffer signal. Please see some of the same references pointed out for split plane. -Jory ----- Original Message ---- From: xuzhengrong <xuzhengrong@xxxxxxxxxx> To: si-list@xxxxxxxxxxxxx Sent: Thursday, August 30, 2007 7:34:03 AM Subject: [SI-LIST] the difference of current profile between power supply path, signal path and return path in a circuit loop Hi all, After scanning the discussion about the return path, I have to think such a question that, what does the current profile in power supply, signal path and return path in a circuit loop look like, and what is the difference of the three ones? As is known to all, in a simple DC circuit such as small bulb loop, current supply is equal to the return current between possive pole and negative pole. Then, in a high speed digital circuit, if only one buffer works and outputs one signal level(excluding multi-signal use the common return path and power supply path ), would current profiles in the signal path and its return path be the same? Furthermore, as the source of the signal current, what is the difference between the current profile in the power supply path and its signal current profile? Thanks for any idea. Zhengrong ------------------------------------------------------------------ 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: http://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: http://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 ____________________________________________________________________________________ Need a vacation? Get great deals to amazing places on Yahoo! Travel. http://travel.yahoo.com/ ------------------------------------------------------------------ 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: http://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: http://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