hello Arpad, having gone through all the replies to my question on SI-list regarding IBIS V-t curves and having read the 2 IEEE papers referred by Herbert, i hope i have understood how and what information the V-I and V-t curves carry with them.The next step is how the simulator interprets it for simulations. And i am trying to figure out how the IBIS models allow simulations for loads other than the R_fixture as you said "waveform will adjust to the loading conditions"(and it should do that). If i have rightly understood, it is the "Transient V-I curves" and the load line intersections that allow this. But for getting Transient V-I curves, alpba and beta values are required. One of the IEEE papers quoted by Herbert says "each set of alpha and beta provides an instantaneous I/V curve for upper and lower devices of the buffer." Obtaining one complete Transient V-I curve(say,for time=t1) from a single alpba and beta is, i suppose, by scaling the dc V-I curve proportionally by factor of alpha and beta. Now with transient V-I curves available, for different loads, new waveform is obtained by plotting voltages(against time) at which each transient curve is intersected by the load line. i am unsure if thats the way things happen. so do comment. regards ADEEL ------------------------------------------------------------------ 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