OK... WRT power... Think it through... Where/What is the load? Is the load passive or dynamic? What is the source current? Is it passive or dynamic? What if you have a passive source and a passive load? Now... What if there is a switched source and a passive load? Now... What if there is a (relatively) passive source and a switched/dynamic load? BR Gus -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Taha Amiralli Sent: Sunday, December 03, 2006 7:53 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Spectre S-parameter based modeling- Stability issues It is likely that applying an inverse DFT, on a freq response obtained by non-passive and non-causal matrices, could result in an unstable time response. I would say that the best approach to this problem would be to try and enforce passivity/causality on the S-parameter matrices as suggested by Madhu and endorsed by Patrick. I would assume that the a simple check of the accuracy of the vector fitted data would be accomplished by comparing the freq response of both the vector fit data and the original data. This would help circumvent the second point brought up by Patrick. I am however curious, if these interconnects are Power lines, why is it that one would require a transient/freq analysis :) Its not like there are timing issues that need to be maintained at each branch in the power line node... Yes there could be the issue of finding out how long it takes power to appear at some obscure end of the device before letting the reset circuitry pull the device out of reset, but cant that be done via theoretical calculations with a bit of extra delay as insuarance? Sincerely, ------------------- Taha Amiralli thamiral [A] uwo [D] ca thamiral [A] gmail [D] com MESc Candidate 2007, Computer Engineering The University Of Western Ontario BESc, BSc. 2005, Computer Engineering & Computer Science The University Of Western Ontario --------------------------------------------------------------- On 12/2/06, Ihsan Erdin <erdinih@xxxxxxxxx> wrote: > > Madhusudanan, > If you're dealing with the power planes there's a good chance the port > loads are linear (decoupling caps and their parasitics, etc.) Then why > bother with the time domain simulations and painful data > constraintment? Just use a linear frequency domain simulator and get > the time domain results by DFT in a straightforward manner. > > Regards > > Ihsan > > On 12/2/06, Madhusudanan K Sampath <mkeezhve@xxxxxx> wrote: > > > > Hi All, > > I am using n-port component in spectre to perform time domain > > simulation using touchstone s-parameter files for power planes which > > are obtained from measurement/full wave tools. In many cases, the > > simulation explodes due > to > > stability reasons. What are the possible causes of this and how can > > one solve this issue. I think Spectre n-port component uses > > convolution methods to perform time domain simulation from frequency > > domain s-parameter data and hence are prone to convergence issues. > > If so how does it enforce > passivity > > in the model. I verified the s-parameter matrix for eigenvalues and > > it proves the data is not passive. I would like to compensate for > > passivity and then re-try the time domain simulation. There are > > quite a few > interesting > > passivity enforcements techniques in literature by Dr. B. Gustavsen > > and > Dr > > S.G. Talocia . However they are applied on the rational functions > > which are obtained by vector fitting the data. My question is if I > > vector fit the data, enforce the passivity using these techniques > > and then > calculate the > > S-parameter matrix for each frequency point from the passive > > rational function model. Will spectre give stable results with this new data ? > > > > Please share your ideas and views on this. Thanks in advance. > > > > Madhu > > > > > > > > > > > > ------------------------------------------------------------------ > > 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 > > > > > > > > > ------------------------------------------------------------------ > 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 > > > -- ------------------------------------------------------------------ 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 ------------------------------------------------------------------ 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