Make sure that you consider not only the maximum frequency. You also need to make sure that your S-parameter set has enough data points to correctly model all the resonances in the measured frequency band. If you have too few data points, and the graph of the S-parameters over frequency looks choppy or jagged, then the model will probably be non-causal. S-parameters are like power tools. A skilled user can get a lot done with them, but if used carelessly, they can hurt you. Weston -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Rajan Hansa Sent: Wednesday, May 18, 2011 3:44 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Maximum Frequency for S-parameter Extraction of Board Power Plane Hello All, I have got a PCB database of one Ethernet Board and I have to extract s-parameter for all power plane from voltage regulator to power pin of chip package. The Board database includes all decap. As we know extraction time is directly related with maximum frequency So while setting maximum frequency for s-parameter extraction, I am bit confused, I would like to know that do I need to set knee frequency ( Fknee = 0.35/Trise) as maximum frequency OR for board level simulation we shouldn't care knee frequency. As per my understanding, package inductance won't allow very high frequency component (switching current component which depends on Trise !!) to travel to board from chip so voltage regulator in board will never see those high switching current so I shouldn't simulate/extract s-parameter till knee frequency. What's expert view on this ? Rgds, Rajan ------------------------------------------------------------------ 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 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 Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu