One further note on the subject regarding frequency: We also found some apps use a constant frequency when determining Gij (you'll have to do the math to determine if this is the case - use the homogeneous symmetric stripline case to eliminate other variables and apply equation (2) below to rapidly verify if this is the case). We checked this by first looking at the units presented in the results of the app (helps in drawing some conclusions), as well as doing some reverse calculation. For example, one app seemed to always use 1e9Hz as the frequency (which loosely translates to 350ps in the time domain for valid range of the model results). Brian Burke http://www.interactive-products.com > > The conductance matrix, Gij, can be calculated from the capacitance > matrix, Cij, by: > > (1) Gij = Cij{ 1-(Eo/Em)(1-tanh((Em/Eo)-1)))}w*tandelta > > where > > Em/Eo is the effective dielectric constant for line i > > If the dielectric is uniformly distributed the approximation: > > (2) Gij=Cij*w*tandelta > > can be used. > > In verifying some applications (such as xtk-xfx) some time ago (it > may not be the case now) we found something very similar to what you > are describing. In a homogeneous stripline situation equation (2) > above was confirmed. However, in a non-homogeneous microstrip > configuration we either found the dielectric material above base > ground was used, or some average dielectric material (as I say, it > has been a while, and would have to go through some notes to > determine exactly the case). > > In any regard, we concluded that some apps do take short cuts (or at > least have in the past). > > I have mentioned before in this forum, and I will again here. You > may download the FREE version of IFSPro EZStack and validate the > models you are creating (specifically G in this instance) against > our application, as we DO NOT base our solution on the above > assumption. > > http://www.interactive-products.com > > Regards, > > Brian Burke > > > > --- In si-list@xxxxxxxxxxxxxxx, "Sogo Hsu" <sogo.hsu@xxxx> wrote: > > > > Hi, Gurus, > > > > One topic confused me for a long time, I look forward somebody > here > > can help me to clarify. To model the dielectric loss for trace, it > > is used to express the conductance as > > > > G(f) = G0 + freq * Gd > > > > where G0 is in terms of leakage current loss at DC and Gd is > > dielectric loss. As I know, Gd is expressed as > > > > Gd = 2* pi * (tan delta) * C > > > > where (tan delta) is loss tangent. and (tan delta) is defined as > > conductivity / (2* pi * freq * epsilon). As a result, > > > > G(f) = G0 + freq * (2*pi*(conductivity)/(2 * pi*freq*epsilon))*C > > G(f) = G0 + (conductivity/epsilon) * C > > > > My questions are > > > > (1) Ideally, G0 is equal to (conductivity/epsilon) * C, as well as > G > > (f) is frequency independent variable! Is it right? > > > > (2) Base on the definition, loss tangent is proportial to 1/freq. > > However, we typically treated loss tangent as a constant versus > > frequency. If loss tangent is a constant, it means conductivity is > > proportion to frequency if we assumed epsilon is stable versus > > frequency. Is it true regarding a constant loss tangent or a > linear > > frequency dependent conductivity? Or, both of them is wrong. > > > > (3) We verify the extracted RLGC file against Hspice in v. > 2004.09. > > We found the Gd is exactly the half of above equation for > Microstrip > > line in inhomogeneous medium. The rsults for Stripline agree with > > the above equation. It seems Gd for Microstrip line is the average > > value of dielectric and free space area. It is reasonable? Does > > anyone verify the same issue before? > > > > Best regards, > > > > Sogo Hsu, Ph. D. > > > > Simulation center/Foxconn > > > > > > > > > > ----------------------------------------------------------------- - > > To unsubscribe from si-list: > > si-list-request@xxxx 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@xxxx with 'help' in the Subject field > > > > List FAQ wiki page is located at: > > http://si-list.org/wiki/wiki.pl?Si-List_FAQ > > > > List technical documents are available at: > > http://www.si-list.org > > > > 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@xxxx 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@xxxx with 'help' in the Subject field > > List FAQ wiki page is located at: > http://si-list.org/wiki/wiki.pl?Si-List_FAQ > > List technical documents are available at: > http://www.si-list.org > > 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 FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org 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