Which simulator are you using? If Hspice or other SPICE-like simulator, it seems likely to me that the problem is simply an artifact of numerical transients in the simulation results. When I create such eye diagrams, I "throw away" the first several bit times for just that reason. Kim Helliwell On Apr 20, 2005, at 5:13 AM, giorgio ravesio wrote: > > > Hi all, > I am doing some simulation on a SATA I bus, and I have noticed an eye > diagram violation when the lenght of the differential pair traces > reduce > down to 2 inches. > The violation is a "glitch" in both the logical level (i.e the logical > higt state is affected by a glith who violate the Vih(min) while the > logical low state is affected by a glitch who violate the Vil(max). > This strange glitch is approximately 100pS long and occurs > approximately 2*Tpd from the leading edge, so I am pretty sure it is > caused by some improper termination. > What is surprising me, is that this violation occurs only in the first > bit of the pattern, i.e if I skip the first bit of the pattern > everything seems OK. > Could anyone tell me if there is a reason why only the first bit has > this strange behavior ? > > Thanks in advance. > Giorgio > > > . > > > > ------------------------------------------------------------------ > 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 FAQ wiki page is located at: > http://si-list.org/wiki/wiki.pl?Si-List_FAQ > > List technical documents are available at: > http://www.si-list.org > > 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 > > > Kim Helliwell kimgh@xxxxxxx Homepage: http://homepage.mac.com/kimgh ------------------------------------------------------------------ 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 FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org 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