Xuzhengrong, you can understand this by looking at a network of multiple unique RLGCs. When trying to represent the network with a simpler single RLGC the values for the most accurate fit depends on what the frequency band is. Steve. xuzhengrong wrote: > Hi, > To simplify the model, we often extract single RLGC parameters from the > s-parameter model at a certain frequency. > I wonder what on earth the meaning of the single frequency parameters is. > First, if the parameters only represent the magnitude and phase of the > S-parameter model at the frequency point, it may have different combinations > of RLGC to reach the same goal, what's the method or principle? > Second, if the parameters are meaningful at a certain frequency, why can > single RLGC parameters often be used to estimate characteristic of package > model such as IBIS? > > In my opinion, for example, the single RLGC model should be the first-order > approximation to the real model for transmission line, as Eric's book > 'Signal Integrity: Simplified' said. > It is equivalent to the real model within low frequency range and we can use > it if the signal frequency component is within the range. > However, if the RLGC model extracted at a certain frequency is only > meaningful for the extracting frequency, it isn't the first-order > approximation for the transmission line. > So we can't use it as the first-order approximation and estimate its low > frequency characteristic. > > > Appreciate any idea and discussion for the problem. > > Best Regards, > 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: > //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 > > > > -- Steve Weir Teraspeed Consulting Group LLC 121 North River Drive Narragansett, RI 02882 California office (866) 675-4630 Business (707) 780-1951 Fax Main office (401) 284-1827 Business (401) 284-1840 Fax Oregon office (503) 430-1065 Business (503) 430-1285 Fax http://www.teraspeed.com This e-mail contains proprietary and confidential intellectual property of Teraspeed Consulting Group LLC ------------------------------------------------------------------------------------------------------ Teraspeed(R) is the registered service mark of Teraspeed Consulting Group LLC ------------------------------------------------------------------ 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