Luciano, How about other lines? Thanks. Mick On Mon, Aug 8, 2011 at 10:52 AM, Luciano Boglione <l.boglione@xxxxxxxx>wrote: > Mick, > > When you enter the delay, the reference planes are set at the edges of the > delay line (i.e. at the probe tips); if you enter a 0 delay, the reference > planes are set at length/2 of the delay line (mid point). > > Take care, > Luciano > > > -----Original Message----- > From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] > On > Behalf Of Jim Nadolny > Sent: Monday, August 08, 2011 10:45 AM > To: Mick zhou; si-list@xxxxxxxxxxxxx > Subject: [SI-LIST] Re: 2 questions about TRL cal > > Hey Mick - > > My 2 cents... > > On the delays - I always measure the delay differences in the line > standards > first, then specify the delays in the cal kit definition. The result has > been pretty good success with the behavior of the extracted models. 4 or 5 > years ago I was starting to dig into all this and was told (by an industry > colleague) that the Agilent code does not use the delay numbers...so just > use 0 ps. When I asked Agilent about that practice they sort of looked at > me like I had 3 heads - yes you need to specify the delay so that is what I > do. To be honest - I can't really answer your question though, just my > experience. > > On the overlap - I use the overlap as a safety measure to cover variations > in substrate performance. Gives me margin when dealing with batch to batch > variations in FR-406. Having the overlap also allows you a range of > frequencies that you can use to intelligently select as a transition > frequency. The selection of the transition frequency can impact the > "steps" > in the measured RL that is characteristic of TRL/M calibration. > > jn > > -----Original Message----- > From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] > On > Behalf Of Mick zhou > Sent: Monday, August 08, 2011 10:19 AM > To: si-list@xxxxxxxxxxxxx > Subject: [SI-LIST] 2 questions about TRL cal > > All, > There are two simple questions about TRL calibration that papers/app notes > are not very clear about. > > 1. Is it necessary to enter delays of lines? > The entries are available in the GUI. I have seen people think the > delays are not necessary and use 0ps for all. The argument is: the delay is > determined as part of the process. According to the theory, S12 and > exp(-gamma*l) are determined to a sign ambiguity. Extra infomation such as > delay is needed to uniquely decide the sign (therefore the phase). > However, > delay may not be a problem for engineers who don't care phases. because > they > don't "see" the difference by looking at magnitudes only. But this could > be > dangerous if the models without correct phases are used in time domain > simulations, the delays could be wrong unless you are lucky the phases are > always within 20-160 degrees (8:1 case). > > 2. Is overlap of frequencies necessary in case of multi-lines? Again it is > related to accuracy of phases. Some believe overlaps can improve phase > accuracy. Some don't believe so. The instrument picks up either the last > (unguided cal) or the prority set by Smartcal (guided cal). So how the > phase > accuracy is improved? > > Thanks > > Mick > > > ------------------------------------------------------------------ > 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