Hi Ria: In the digital SI world, Scattering Parameter (aka: S-Parameter; Touchstone) models are often used to describe passive parts of an interconnect. (E.g., package models, connectors, vias, typically any part of the channel that's passive, or even an entire backplane.) Causality: In these S-Parameter or Touchstone models, you can't have an effect that precedes its cause. (E.g., the lights turning on before you've thrown the switch.) Passivity: A passive S-Parameter interconnect model cannot create energy. =20 Checking a model for passivity and causality is another (longer) discussion. Mentor users (HyperLynx, ICX, ICX Pro) are provided with something we call the Touchstone Viewer, which allows them to check a model for passivity and causality, among a number of other things. =20 Bill Hargin High-Speed Marketing Manager Mentor Graphics Corp. Systems Design Division 425-301-4425 - Mobile=20 =20 > -----Original Message----- > From: si-list-bounce@xxxxxxxxxxxxx=20 > [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Ria R > Sent: Thursday, December 06, 2007 9:58 PM > To: si-list@xxxxxxxxxxxxx > Subject: [SI-LIST] Passivity/Causality >=20 > Gurus, > I have heard these 2 terms alot in the world of SI:=20 > Passivity and Causality. > I tried googling it and I dont seem to get what I am lookimg for. > Can someone please throw some light on the definitions of=20 > these 2 terms and what significance they have in Signal Integrity? > Thanks in advance, > Best Regards, >=20 > Ria. >=20 >=20 > =20 > ______________________________________________________________ > ______________________ > Looking for last minute shopping deals? =20 > Find them fast with Yahoo! Search. =20 > = http://tools.search.yahoo.com/newsearch/category.php?category=3Dshopping >=20 > ------------------------------------------------------------------ > To unsubscribe from si-list: > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field >=20 > or to administer your membership from a web page, go to: > //www.freelists.org/webpage/si-list >=20 > For help: > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field >=20 >=20 > List technical documents are available at: > http://www.si-list.net >=20 > List archives are viewable at: =20 > //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 > =20 >=20 >=20 ------------------------------------------------------------------ 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