Hi all, Thank you very much for your prompt response. Well, I think it is difficult to discuss something when you don't know any details about the used models and=20 simulation tools. So, here they are. For the simulation I used the following IBIS model which can be downloaded from the TI website at: CDCV850 IBIS Model (SCAM025, 49 KB - Updated: 06/20/2002) http://www-s.ti.com/sc/psheets/scam025/scam025.ibs TL: Z0=3D60Ohm, Td=3D0.5ns, Clock Frequency=3D100MHz |\ Y0 ____ | \-----|____|---|=20 | \ TL |_ | / | | | 60R | / _TL_ |_| |/=B0-----|____|---|=20 Y0- =20 Y0-: CDCV850_DOUT, Y0: CDCV850_DOUT=20 As I mentioned in my previous email, I performed the simulation=20 with two common simulation tools. These tools were Hspice 2002.2=20 and SpecctraQuest 14.2. I've also performed the same simulation=20 with older releases, but they show all the strange behavior. The output signals from Y0 and Y0- cross near the low voltage=20 state instead of in the middle of the high and low state. From my point of view it seems, that SpecctraQuest as well as=20 Hspice have problems to compute the correct waveforms,=20 because I have compared these results with HyperLynx (Innoveda),=20 Hot-Stage (Zuken), XTK and a simulation result based on an Hspice=20 transistor level model. These results look quite well. Maybe someone of you has an idea about the differences in=20 handling IBIS files or what I should do to get good=20 simulation results. Many thanks, Dirk. =20 > -----Urspr=FCngliche Nachricht----- > Von: Linnenbruegger Dirk=20 > Gesendet: Donnerstag, 19. September 2002 13:37 > An: 'si-list@xxxxxxxxxxxxx' > Betreff: [SI-LIST] Simulation problems with SSTL2 IBIS model=20 >=20 >=20 >=20 >=20 > Hi SI-List members, >=20 > I have performed some simulations using an IBIS=20 > model of a differential clock buffer and I wonder=20 > about the strange waveform behavior.=20 > The simulations have been computed with two very=20 > common simulation tools. >=20 > The output signals cross near the low voltage state=20 > instead of in the middle of the high and low state. > Furthermore high ringing occurs although the=20 > transmission lines are terminated properly. >=20 > After some investigations of the IBIS file I found=20 > out, that the simulation results look much better,=20 > if the [ramp] data will be used instead using the=20 > [rising/falling waveforms]. >=20 > But, of course these simulation results based on the=20 > ramp data don't correlate very well to the reference=20 > waveforms, which are based on an Hspice transistor=20 > level model. Therefore I tried to get some more=20 > simulation results which have been computed with some=20 > other tools. I was really surprised, that the new=20 > results of the other tools look quite well. >=20 > From my point of view it seems, that the IBIS file is=20 > OK and that there might be some problems in our tools=20 > to handle this kind of IBIS file. >=20 > So, I would like to know if someone of you had similar=20 > problems or an idea how to solve this problems. >=20 >=20 > Thanks > Dirk Linnenbruegger =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 > 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=20 > Old (prior to June 6, 2001) list archives are viewable at: > http://www.qsl.net/wb6tpu > =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 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