Muniswara, Thanks for your interest in IBIS! Please note that traditional IBIS (i.e., IBIS based on tables of I-V and V-t data, plus C_comp) does not include any information about the buffer's stimulus from the core, latches, die logic, etc. So, the timing measurement parameters Rref, Cref, Vref and Vmeas do not characterize Tco, Tvalid or any clock-to-output or core-to-output behavior. The IBIS timing measurement parameters only describe the load used to characterize the time taken by the output to reach the given measurement level (Vmeas) from the stimulus edge presented to the IBIS model by the simulator. Therefore, you may see a difference in delay time between the output from a SPICE transistor-level model and an IBIS model of the same buffer into the same load. The overall shape of the waveform after the transition begins should be identical, however, depending on the quality of the IBIS model. Some good presentations on these topics can be found on the IBIS website at: http://www.eda.org/ibis/training/ I hope this helps! - Michael Mirmak Intel Corp. Chair, IBIS Open Forum http://www.eigroup.org/ibis/ http://www.eda.org/ibis/ ------------------------------------------------------------------------ Hi, If Timing Measurement Conditions describing parameters (Vmeas Rref Vref Cref) are included in a model, Does this imply that the delay ( core i/p to pad ) of IBIS or SPICE Buffer with this load conditions and measured at Vmeas will be same. Tdelay (Vmeas Rref Vref Cref ) (IBIS) = Tdelay (Vmeas Rref Vref Cref ) (SPICE/Lab measurement) Tdelay <= Delay from input to Pad With regards, Muniswara Reddy . V Design engineer, PIPD-IO group, Bangalore. -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. -------------------------------------------------------------------- |For help or to subscribe/unsubscribe, e-mail majordomo@eda-stds.org |with the appropriate command message(s) in the body: | | help | subscribe ibis <optional e-mail address, if different> | subscribe ibis-users <optional e-mail address, if different> | unsubscribe ibis <optional e-mail address, if different> | unsubscribe ibis-users <optional e-mail address, if different> | |or e-mail a request to ibis-request@eda-stds.org. | |IBIS reflector archives exist under: | | http://www.eda-stds.org/pub/ibis/email_archive/ Recent | http://www.eda-stds.org/pub/ibis/users_archive/ Recent | http://www.eda-stds.org/pub/ibis/email/ E-mail since 1993Received on Sun Apr 13 20:57:41 2008
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