Hi Yan, IBIS models before v4.0 do not contain any internal delay modeling. I think it is quite normal to see an offset between IBIS simulation results and SPICE simulation results if you line up internal digital excitation waveforms. I am not sure if the latest IBIS standard adds any new feature related to internal delay. =20 Disclaimer: The content of this message is my personal opinion only and although I am an employee of Brocade Communications Systems, the statements I make here in no way represent Brocade's position on the issue, nor am I authorized to speak on behalf of Brocade on this matter. Thanks=20 Tony -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of yan hang Sent: Sunday, November 19, 2006 8:32 PM To: si-list@xxxxxxxxxxxxx Cc: liuweidong@xxxxxxxxxx Subject: [SI-LIST] Re: Buffer delay Hello Lynne & Michael , In the "IBIS QUALITY SPECIFICATION ", it defined that the IQ3=3D20 level--the model data for timing analysis has been checked. If there is =3D a time of offset between the two waveforms(IBIS &HSPICE),shoule we say the model can not pass the IQ3? When we use hspice model to create ibis model ,do we must check the =3D offset and correct it? Best Regards, Yan Hang Huawei Technology Shanghai Research Institute Interconnection Dept.,R&D Tel =3DA3=3DAB862168644808=3DA3=3DAD24043 -----=3DD3=3DCA=3DBC=3DFE=3DD4=3DAD=3DBC=3DFE----- =3DB7=3DA2=3DBC=3DFE=3DC8=3DCB: Lynne D. Green = [mailto:lgreen22@xxxxxxxxxxxxxx]=3D20 =3DB7=3DA2=3DCB=3DCD=3DCA=3DB1=3DBC=3DE4: = 2006=3DC4=3DEA11=3DD4=3DC218=3DC8=3DD5 3:36 =3DCA=3DD5=3DBC=3DFE=3DC8=3DCB: forsilist@xxxxxxxxx; yang@xxxxxxxxxx; = =3D si-list@xxxxxxxxxxxxx =3DB3=3DAD=3DCB=3DCD: liuweidong@xxxxxxxxxx =3DD6=3DF7=3DCC=3DE2: RE: [SI-LIST] Re: Buffer delay Hello, Yan Hang, IBIS and SPICE do not have the same Time=3D3D0 reference, due to the way = =3D SI tools trigger I/O inputs. This means that there is a time offset =3D between the two waveforms. This offset can be corrected for by simulating the load [Vmeas, Rref, = =3D Cref]. This delay offset can then be used to adjust the delay in other =3D simulations. Many SI tools have automated this process. A good paper on this is http://pcdandm.com/cms/content/view/2800/95/. = =3D There is also a HyperLynx Application Note, referenced in that paper. Best regards, Lynne "IBIS training when you need it, where you need it." Dr. Lynne Green Green Streak Programs http://www.greenstreakprograms.com 425-788-0412 lgreen22@xxxxxxxxxxxxxx -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =3D On Behalf Of raj singh Sent: Friday, November 17, 2006 1:34 AM To: yang@xxxxxxxxxx; si-list@xxxxxxxxxxxxx Cc: liuweidong@xxxxxxxxxx Subject: [SI-LIST] Re: Buffer delay Hspice delays should be accurate and in general more than ibis. Better = =3D to use ibis only for SI sims and not for timing. =3D20 regards Raj yan hang <yang@xxxxxxxxxx> wrote: =3D20 Hi All, Now I do some board timing simulations . I got the hspice =3D3D model = and =3D ibis model for same buffer. Then I set a test fixture(Ex. Cref=3D3D3D15pf,Rref=3D3D3D1E6,Vref=3D3D3D3.3V),I contrast the = simulation =3D result of =3D3D buffer dealy using hspice model and ibis model. I found there is a =3D little big diffrence between them. So when translate hspice model to ibis model,how to consider about the buffer deley issue? =3D3D20 Should I trust the buffer delay value from = =3D ibis model =3D3D simulation? Best Regards. Yan Hang Huawei Technology 086-21=3D3DA3=3D3DAD68644808=3D3DA3=3D3DAD24043 ------------------------------------------------------------------ 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: =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 ------------------------------------------------------------------ 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