Rula, The way to measure the power planes is with a VNA using what is called the two port method. What you do is basically put 2 probes in parallel. This is similar to a 4 point Kelvin measurement. The plane impedance is calculated using S21. This method can be used to make measurements in the milliohms over a range of a few GHz. Check out the paper "Frequency Domain Power Distribution Measurements - An Overview" by Istvan Novak. It was given at DesignCom East 2003 goes into the details. Agilent also has some app notes. Search on their site. I've used this method myself and have got very good correlation to simulations. Frank Frank Paglia Enterprise Engineering Signal Integrity Team Dell, Inc. Frank_Paglia@xxxxxxxx 512 724-8520 Office 512 283-3988 Fax -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of rula.bakleh@xxxxxxxxxx Sent: Thursday, August 06, 2009 1:53 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Power Integrity Measurments Hi Everyone, I'm trying to validate our power integrity tools/simulations and I would like to make some power integrity measurements of our planes. With respect to performing these measurements, I plan to use a Vector Network Analyzer (VNA) to measure the plane impedances of a bare PWB and a PWB with a voltage plane that is populated with only caps in order to correlate these measurements to the simulations. I also plan to measure the plane impedance of a fully populated PWB, just to see the effects that other parts' impedance/mounting would have on the plane impedance. I also plan to use a spectrum analyzer to measure the plane noise spectrum of a powered up module and use an oscilloscope to measure absolute levels of this noise. The purpose of using a spectrum analyzer/oscilloscope is to measure the simultaneous switching effects on the plane, hoping to isolate the PWB effects from internal SSO effects of a component. My dilemma is the following: The VNAs are optimized for 50 ohms and plane impedances of PWBs are designed for very low impedance (most of the time much <1.0 ohm). 1) Due to the impedance discontinuities, what is the expected accuracy of such a measurement? All the research I have conducted concerning PWB impedance measurements points to using a VNA. During my discussions with an Agilent FAE, he recommended using an Impedance Analyzer vs. VNA to measure the PDS of a plane. He also recommended using a high impedance active solderable probe with the impedance analyzer with it being calibrated out to make this measurement. 2) What is the best equipment to use to measure the PDS of a PWB (VNA or Impedance Analyzer)? 3) If the answer is an Impedance Analyzer, is the approach described above correct? 4) Can somebody validated my approach for this type of analysis/measurements? Thank You, Rula ------------------------------------------------------------------ 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 ------------------------------------------------------------------ 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