Hello, great question...I recently had an ASIC house create some models for an = ASIC they were making for us. I could tell by our talks that they were = fairly new to IBIS ("we've done a few of them, but the guy who used to do them is = now a manager"). how did we qualify the models? I had them take their spice model, which = they were very confident in, and create a 1 foot long 50 t-line. They sent = me the plots and I compared them with my sim's using their ibis model in the = same type of circuit. I look closely at the porch at the driver (source Z) = and the rise and fall times at the same place in both circuits. I also try = to make sure nothing else is significantly different. this test would have been very easy for the semiconductor vendor to do = - but they first need very good spice models. best regards, Jim Peterson -----Original Message----- From: Todd Westerhoff [mailto:twester@xxxxxxxxxxx] Sent: Monday, March 25, 2002 6:28 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: IBIS Model Quality (or lack thereof) Oh no, here we go ... For the record, we've had *VERY* good luck getting HSpice to correlate = with IBIS simulations - the problem is, we've had to create most of the IBIS models ourselves ir order to get things to match. Please, let's save the "ultimate HSpice accuracy" arguments for another thread (preferably one that gets redirected to /dev/null). I'm well = aware of IBIS' limitations, and we've done lots of real-world comparisons for = our current applications. IBIS will work just fine if we have decent = models ... AND, I'll be able to do all the post-route analysis I want. The question remains, folks ... what semiconductor vendors are willing = to "step up the plate" and tell us how they test their IBIS models to = ensure correlation to a known source (measurement or HSpice)? Inquiring minds want to know! Todd ;-) Todd Westerhoff Signal Integrity Engineer Hammerhead Networks 5 Federal Street - Billerica, MA - 01821 email:twester@xxxxxxxxxxx - ph: 978-671-5084 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D "I=92m starting With the man in the mirror I=92m asking him to change his ways And no message could have been any clearer If you wanna make the world a better place Take a look at yourself, and then make a change" - "Man in the Mirror", Michael Jackson -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Chris Cheng Sent: Monday, March 25, 2002 5:18 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: IBIS Model Quality (or lack thereof) Why use IBIS at all ? If you are convinced that IBIS is not good enough (which I am), don't simulate and just follow whatever the vendors design rules say. After = =3D all, if you deviate from the rules based on your incorrect IBIS models, do = =3D you think the vendor will really take responsibility if it doesn't work ? = =3D If you follow the design rules, what value does the simulation add to you =3D design ? If you are serious enough to simulate, you must be working on something = =3D that is unique about your own system that needs to be custom optimized =3D beyond what the component guideline can tell you. Get the SPICE model and do a = =3D good job of modeling your own system. If a small little start up like mine = =3D can get SPICE model from vendors, anyone can. Its just a matter of a few = =3D NDA and extra effort. -----Original Message----- From: Todd Westerhoff [mailto:twester@xxxxxxxxxxx] Sent: Monday, March 25, 2002 12:59 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] IBIS Model Quality (or lack thereof) Hi all, We have been doing a lot of comparisons between IBIS and HSpice models lately, with a lot of less-than-satisfactory results. I have an open question for the semiconductor suppliers among us: What testing is performed after an IBIS model is created, to ensure =3D that the completed model behaves as expected? I'm interested in responses from vendors that actually SIMULATE the IBIS model before distributing it = =3D for customer use. It looks to me as though many of the models I've =3D received were never used in a simulation before being released ... and, as a potential customer, I find that quite disheartening. So the question is - what processes are being used to test IBIS models = =3D and ensure they function properly before their release to customers? As always, replies both on and off the list are greatly appreciated. Todd. Todd Westerhoff Signal Integrity Engineer Hammerhead Networks 5 Federal Street - Billerica, MA - 01821 email:twester@xxxxxxxxxxx - ph: 978-671-5084 =3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D= 3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D =3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D= 3D=3D3D=3D3D=3D3D=3D3D=3D3D "I=3D92m starting With the man in the mirror I=3D92m asking him to change his ways And no message could have been any clearer If you wanna make the world a better place Take a look at yourself, and then make a change" - "Man in the Mirror", Michael Jackson ------------------------------------------------------------------ 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: =3D20 //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages=3D20 Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu =3D20 ------------------------------------------------------------------ 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: =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 ------------------------------------------------------------------ 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