Then it looks like you might have case of high side ringback if better margins are when Vref is lower. there are several things you can try : *make sure the GTL bus is terminated at the end of the bus - most likely cause and the CORRECT spec values is applied - i.e. turn ON the compensation circuitry if exists :-) *identify the failing bit and make sure the layout guidelines were implemented correctly. *verify edge rates to be within the spec (@ driver and receiver) When Vref margins are better if Vref is higher , low side ringback is likely the case here : * make sure the NMOS compensation works properly - * layout guidelines * edge rates This is a very generic answer to very generic question :-) -----Original Message----- From: Gupta, Naveen [mailto:naveen@xxxxxxxxx] Sent: Friday, August 30, 2002 10:56 AM To: 'adrian.c.grigoras@xxxxxxxxx' Subject: RE: [SI-LIST] Re: GTL buffers Vref Adrian, Thanks for your answer. They are obtained at preliminary system validation. Thanks, Naveen -----Original Message----- From: Grigoras, Adrian C [mailto:adrian.c.grigoras@xxxxxxxxx] Sent: Friday, August 30, 2002 10:54 AM To: Gupta, Naveen; 'si-list@xxxxxxxxxxxxx' Subject: [SI-LIST] Re: GTL buffers Vref Can you please define "better results" ? Are they obtained in simulation or design validation ? -----Original Message----- From: Gupta, Naveen [mailto:naveen@xxxxxxxxx] Sent: Friday, August 30, 2002 10:46 AM To: 'si-list@xxxxxxxxxxxxx' Subject: [SI-LIST] GTL buffers Vref Hi all, I have a basic question about the Vref for GTL input buffers. If the Vref spec states a 1.0 Volts, but better results are obtained at a lower voltage, what should be the issues one should examine. Relatedly, if better results in turn are obtained at a higher voltage, then what should one examine? Thanks for your answers. Thanks, Naveen ------------------------------------------------------------------ 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 ------------------------------------------------------------------ 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 ------------------------------------------------------------------ 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