From: Dawson Yee <daws...@microsoft.com> List-Post: emc-pstc@listserv.ieee.org Date: Thu, 28 Sep 2000 14:15:33 -0700
If you are doing A vs B comparisons, then just use some resistors to safely voltage divide the input voltage, present a high enough measurement instrument input impedance (preventing the power plane from "seeing" 50 ohms!), feed with a coax cable and then use the measurement instrument attenuator if needed. If you use DC blocking caps you have to be concerned about frequency roll-off (the higher frequencies rolls-off, tricking you into thinking that there are no high frequency issues). With this technique you can (sort of) ascertain the Power and Ground plane noises when used with a spectrum analyzer (don't connect the ground lead, but be aware of what potential it is at). I've used this technique for many, many years (despite a lot of skeptics), have not blown out any instruments, and have had a lot of real world, high volume success. Regards, Dawson _______________________________________________________________________ Free Unlimited Internet Access! Try it now! http://www.zdnet.com/downloads/altavista/index.html _______________________________________________________________________ ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson: pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
