I validate mine by building test PCBs. Lee > [Original Message] > From: <kevin.voegele@xxxxxxxxxxxxxxxx> > To: Lee Ritchey <leeritchey@xxxxxxxxxxxxx> > Cc: fei xue <harrison_cls@xxxxxxxxxxxx>; Istvan Novak <istvan.novak@xxxxxxx>; <si-list@xxxxxxxxxxxxx>; <si-list-bounce@xxxxxxxxxxxxx> > Date: 5/13/2010 9:39:44 AM > Subject: [SI-LIST] Re: AC series capacitor position in high speeddifferentialsignals > > Who validates the measurements? I don't think any methodology is > infallible. > > Kevin > > ******************************************************* > Kevin Voegele > Design Engineering Manager > Toshiba America Electronic Components, Inc > Minneapolis Design Center > ph. 952.842.2476 FAX 952.893.8031 > cell 952.334.1015 > e-mail: kevin.voegele@xxxxxxxxxxxxxxxx > ******************************************************* > > > > Lee Ritchey > <leeritchey@earth > link.net> To > Sent by: "Istvan Novak" > <si-list-bounce@f <istvan.novak@xxxxxxx> > reelists.org> cc > "fei xue" > <harrison_cls@xxxxxxxxxxxx>, > 05/13/2010 11:27 si-list@xxxxxxxxxxxxx > AM Subject > [SI-LIST] Re: AC series capacitor > position in high speeddifferential > signals > > > > > > > > > > > I would maintain from my measurements that the reflections are negligibly > small. > > I would also maintain that simulation results, no matter what the tool or > operator, should not be trusted until they are validated by measurements to > insure the modelling is accurate. I've seen too many simulations done > incorrectly which were used to develop design rules that were either > ineffective or caused problems that I, for one, will not use the results of > unvalidated simulations. > > Each engineer can make up his or her own mind on this, but my experience > says validate simulation results before betting any money on them. > > I'm not trying to offend anyone who does simulations, just advising proceed > with caution. > > Lee > > > > [Original Message] > > From: Istvan Novak <istvan.novak@xxxxxxx> > > To: Lee Ritchey <leeritchey@xxxxxxxxxxxxx> > > Cc: fei xue <harrison_cls@xxxxxxxxxxxx>; <si-list@xxxxxxxxxxxxx> > > Date: 5/12/2010 8:55:32 PM > > Subject: Re: [SI-LIST] Re: AC series capacitor position in high > speeddifferential signals > > > > Lee, > > > > As it was pointed out in earlier threads, location does make a > > difference unless reflections are > > negligibly small. Assuming linearity, when we move components around, > > reciprocity prevails, > > but voltage transfer function from source to load will change, which in > > turn impacts eye > > parameters. > > > > Regards, > > > > Istvan Novak > > Oracle-America > > > > > > Lee Ritchey wrote: > > > This has been answered before on this forum. Since the circuits are > > > linear, it does not matter from a signal integrity point of view. > > > > > > Lee > > > > > > > > > > > >> [Original Message] > > >> From: fei xue <harrison_cls@xxxxxxxxxxxx> > > >> To: <si-list@xxxxxxxxxxxxx> > > >> Date: 5/12/2010 11:35:49 AM > > >> Subject: [SI-LIST] AC series capacitor position in high speed > > >> > > > differential signals > > > > > >> Hello all, > > >> We often can get different guideline of placing capacitor position > when > > >> > > > placing AC series capacitor on high speed differential signals, like > PCIe, > > > SAS or LVDS signals. sometimes we followed the guideline to put > capacitors > > > near driver, sometimes near multi-connection connectors or sometimes > put it > > > near receivers. > > > > > >> Could anybody tell me what is the consideration of capacitor placing > > >> > > > position? Thanks! > > > > > >> Harrison > > >> > > >> > > >> > > >> > > > ------------------------------------------------------------------ > 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 > ------------------------------------------------------------------ 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