Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Todd, Thanks. See below my follow-up question. Todd Westerhoff wrote: > Hi all, > > There were a lot of parts to this thread, but I wanted to comment on: > > (5) The Interconnectix (ICX) simulator also provides a means for > automatically compensating for the load difference between the test load and > the actual PCB trace load. > > >> I think most, if not all, of the IBIS simulators have this capability. > The different vendors give it different names and have somewhat different > options, but it's basically the same concept with different implementation > details. > > But this method depends, of course, on the manufacturer to supply the > appropriate test load parameters. Since the IBIS model, on which ICX > simulations are based, assumes a certain configuration of test capacitance > and resistance, this presents a problem where the manufacturer uses a > different configuration. For example, I encountered a manufacturer who > claimed he used a current-source test load, with a different current load > for the high and low states of the tested outputs. I had to use > approximations in order to be able to simulate these outputs using an IBIS > model. Has anyone encountered such a problem and have a solution? > > >> First and foremost, you're doing the right thing, and that is paying > close attention to the correlation between the manufacturer's spec and > what's in the IBIS model. The situation you describe is one common problem, > spec'ing a high speed part into a large capacitive (lumped) load is another > common one. > > >> For your specific case, the easiest solution may be to disable the > simulator's buffer delay adjustment and report the raw data instead. You > then simulate the different test load conditions individually, determine the > adjustment factor for each case and adjust the raw data in whatever manner > you like (as in, Excel). Alternatively, some tools allow you to load the > delay adjustments into the library directly, and use these values to perform > the correction. > >> Actually, I'm not sure how to understand your advice, as related to my specific problem. Can you elaborate a little? > >> The base problem you identified - limitations of the existing IBIS spec > in specifying test loads, is, I believe, a recognized issue. > > Hope that helps, > > Todd. > > Todd Westerhoff > SI Engineer - Hammerhead Networks > 5 Federal Street - Billerica, MA - 01821 > email:twester@xxxxxxxxxxx - ph: 978-671-5084 > ============================================ > > "Oh, but ain't that America, for you and me > Ain't that America, we're something to see > Ain't that America, Home of the Free > Little pink houses, for you and me" > > - John Mellencamp > > ------------------------------------------------------------------ > 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 -- Itzhak Hirshtal Elta Electronics POB 330 Ashdod Israel 77102 Tel : 972-8-8572841 Mobile: 972-64-238631 Fax : 972-8-8572978 email: hirshtal@xxxxxxxxxxxxx ------------------------------------------------------------------ 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