> -----Original Message----- > From: MikonCons@xxxxxxx [mailto:MikonCons@xxxxxxx] > Sent: Monday, September 10, 2001 6:30 PM > To: si-list@xxxxxxxxxxxxx > Subject: [SI-LIST] Re: Tightly coupled VS loosely coupled diff pairs ...[snip]... > Another major contributor in edge rate degradation is non-symmetrical > coupling to adjacent signal traces and pins in connector pin > fields. Contrary > to recommendations made by another well-known consultant for AMP HS-3 > connectors, I have conclusively demonstrated superior eye > diagram performance > of pairs that bracket the signal pin rows, as opposed to the > ground pin rows. Thanks, Mike, for an enlightening response. Some folks claim that loose coupling is better because it results in less reflection due to intra-pair trace spacing changes (hence impedance mismatches) in connector pin fields, in device break-out area and associated vias. You didn't say much about that. Just wondering, have you ever quantified that particular reflection effect? Around the same impedance matching issue, is it not the case that in some applications there is a need to tightly match both single-ended and differential impedances? If that is the case, is it then always right that tight coupling is better than loose coupling? Thanks. Hassan. ------------------------------------------------------------------ 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 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