My favorite analogy is the data sheet. What if the typical data sheet was as accurate as the typical IBIS file? On Tue, 2002-03-26 at 11:22, Dunbar, Tony wrote: > > All, > > As with other threads on the SI List, we are teetering on the brink of > getting away from the original question or topic. I apologize to Todd > up-front for pitching in and contributing further to the distractions with > my own comments. I also applaud Adam for his contribution and those he has > made in the past because, as far as I'm aware, he's the only Si vendor IBIS > model-maker that I ever see on the List. I'm ready to be flamed for that, > but I suspect I won't feel much heat because, somewhat indicative of the > problem, there are so few other IBIS model-makers on the List and/or have > any affinity for the end-user situation, as Todd indicated in his opening > post. > > As regards the matter of IBIS model "cleansing service" and using that term > as a eupemism for "sanitization", I'm afraid the latter is often the more > appropriate one to use. The fact that this should even be necessary for a > simulation model is quite appalling to me. I, along with my customers, have > fought this for over 7 years. I know there are many on the list who have > fought it for longer. Please note that I am not saying that a model should > not be checked when it is received and prior to being used; that's only good > engineering practice. > > But let me ask the following question, which, though stated in hypothetical > terms, it is not too wide of the mark: > > If your ASIC or FPGA or any other Si vendor supplied digital simulation > models (e.g. VHDL or Verilog) to the same quality that many IBIS models are > supplied, would the industry tolerate it to the same extent poor quality > IBIS models are tolerated? > > Sorry, but poor quality IBIS models is a pet subject of mine, since it > consumes so much of my time and that of my customers. > > Regards, > Tony > > -----Original Message----- > From: Joe Socha [mailto:Joe.Socha@xxxxxxxxxx] > Sent: Tuesday, March 26, 2002 9:45 AM > To: si-list@xxxxxxxxxxxxx > Subject: [SI-LIST] Re: IBIS Model Quality (or lack thereof)- Cleansing > service > > > > Hello All, > > It is matter of Knowledge and Time. And, as we all know time is money. > Yes the Vendors need to be IBIS savvy, and they have to want to put in the > time to check their models. I believe Todd is asking the semiconductor > community to let us know which of them takes the time to check / test/ > verify/ correlate their models before releasing them to the public. ( I just > saw the response from Adam at Fairchild.) > > Plexus provides engineering and SI services, and as such we cleanse all the > model we use. (I prefer to describe it as cleansing rather than Sanitize > because sanitize sounds too drastic.) This includes reviewing all the data > testing, modifying the model as needed, working with the vendor as > necessary, testing the model on some standard loads and other activities > such as that. Unfortunately or fortunately depending on your point of view, > the cleansed model is owned by the customer paying for the work we do. This > becomes a competitive advantage for our customer, but unfortunately does not > benefit the overall user community > > I like to use the free " Visual IBIS editor" from Innoveda ( formerly > Hyperlynx) There is a new version ( V 3.0) on the web site, and it has some > significant improvements over V2.0. As with all tools it is not perfect, but > it is a time saver for me. > http://www.innoveda.com/products/datasheets_HTML/ibis.asp When dealing the > semiconductor supplier I always ask them to download it so we can talk" > apples to apples" for comparisons and understandings. We have also produced > some models for semiconductor companies and we run the models in several of > the simulators and overlay the results to show that under some typical > topologies the models/simulators all produce similar results. > > So it comes down to time. Somebody has to put in the time. The semiconductor > company, the user, or outsourcing. > > > Thanks, > Joe Socha > ---------------------------------------------------------------------------- > ------- > Joe Socha: Technical Lead, Signal Integrity Analysis > Plexus Technology Group > Snail Mail: 400 Amherst Street Nashua, NH 03063 > Email: joe.socha@xxxxxxxxxx > Direct: 603.864.1334, Fax: 603.864.1301, Main: 603.864.1300 > ---------------------------------------------------------------------------- > ------- > > -----Original Message----- > From: pwelling@xxxxxxxxxxxxxx [mailto:pwelling@xxxxxxxxxxxxxx] > Sent: Monday, March 25, 2002 6:56 PM > To: twester@xxxxxxxxxxx; si-list@xxxxxxxxxxxxx > Subject: [SI-LIST] Re: IBIS Model Quality (or lack thereof) > > > Todd, > > Many IBIS Models will indicate in the comments section that they are a = > SPICE > to IBIS conversion or a Benched model. Even though they say they are = > bench > models, sometimes they don't correlate very well because test = > conditions > versus real world loading are two different things sometimes. Sometimes = > the > power supply / ground isn't as clean as desired, load impedance varies = > with > trace topology, etc. > > I have had reasonable correlation on some models and some not.=20 > > The first thing (in my oppinion) that needs to done is to at least = > parse the > models - before they are published. So many times I have opened models = > just > to find stupid little syntax problems and things like 1/0 Buffer = > (instead of > I/O Buffer) for the I/O type. They could not have parsed it before > publishing it, so how did it run when they tested the model - and on = > what > simulation tool? Do vendors test the model on more than 1 tool, it's > supposed to be universal, but I think they would be surprised how the = > model > might behave. > > I opened one today (a new device) that had several errors in it - = > stupid and > complex. > > Then there is the problem of what revision IBIS models the Simulator = > will > support. On older simulators, I have had to strip out 3.x model = > information > to get them compile or to even run without hanging up the system. > > IBIS can work, as long as you know the models, where they came from, = > have > "sanitized" them, and your simulator will support them. Generally, you = > can't > just use them off of the web without some work. Some model houses will > create them for you, but be sure you understand what you are getting. = > Some > just SPICE to IBIS, some create minimal point models, dV/dT's are = > typical > (whatever that is), etc. > > Yes, SPICE will give more accurate results, take longer to run, and are > generally not applicable for routed board level trace simulation within > budget and schedule constraints. > > I agree with you that we need help with IBIS models and it has to = > originate > with both the device vendor and simulator vendor. > > > Philip Ross Wellington > Mgr. Signal Integrity & EMI > L-3 Communications CSW > > > -----Original Message----- > From: Todd Westerhoff [mailto:twester@xxxxxxxxxxx] > Sent: Monday, March 25, 2002 4:28 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 > > "starting With the man in the mirror > 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 = > > all, > if you deviate from the rules based on your incorrect IBIS models, do = > > you > think the vendor will really take responsibility if it doesn't work ? = > > If you > follow the design rules, what value does the simulation add to you > design ? > If you are serious enough to simulate, you must be working on something = > > that > is unique about your own system that needs to be custom optimized > beyond > what the component guideline can tell you. Get the SPICE model and do a = > > good > job of modeling your own system. If a small little start up like mine = > > can > get SPICE model from vendors, anyone can. Its just a matter of a few = > > 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 > that the > completed model behaves as expected? I'm interested in responses from > vendors that actually SIMULATE the IBIS model before distributing it = > > for > customer use. It looks to me as though many of the models I've > 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 = > > 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 > > > "starting With the man in the mirror > 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 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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 > > -- ============================================================================= Mike Mayer mwmayer@xxxxxxx ------------------------------------------------------------------ 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: 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