> As the ground is thought as a zero point, nothing can propagate through > it. > > Unless the ground has resistance or inductance, but then it's not a ground.
Dr. Howard Johnson's site and news letter has some interesting things to say about "ground". http://www.sigcon.com . http://www.sigcon.com/newsletter.htm is worth looking at. This email came in on Friday, but I can not yet find it on his site, or I would just post the link : [hsdd] High-Speed Digital Design Newsletter - Reason for Ground Splits From: "Dr. Howard Johnson" To: hsdd AT freelists.org Date: Friday 08:02:53 pm REASON FOR GROUND SPLITS HIGH-SPEED DIGITAL DESIGN - online newsletter - Vol. 9 Issue 04 [snip] Dr. Johnson replies: If you are not familiar with them already, check out these three background articles before proceeding: ADC Grounding (predecessor to the article you mention) http://www.sigcon.com/Pubs/edn/adcgrounding.htm Multiple ADC Grounding (which you already found) http://www.sigcon.com/Pubs/edn/multipleadc.htm Common-mode Ground Currents (presents a terrific visualization of the problem) http://www.sigcon.com/Pubs/news/7_02.htm [snip] [End Newletter] See also http://www.sigcon.com/pubsChron.htm : * Visible Return Current return current -- I may at last have found a way to demonstrate, in a direct (and dramatic) fashion, to any observer, where and how high-frequency current flows in a printed circuit board. * Ground Bounce Calculations high-speed digital design formulas [Why latches do strange things.] * Ground/Power Planes grounding, layer stack, power system -- At very high speeds, bypass capacitance needs to be within less than 1/10 of a rising-edge-length in order to function effectively. * Probing High-Speed Digital Designs probes -- In high-speed system developments, the ubiquitous 10-pF 10:1 capacitive-input probe is no longer adequate. The two alternatives are the FET-input probe and the resistive-input probe. Those are three of many years worth of tips. I realize a furnace controller is not "High Speed" but electrons still move darn fast... :-)
