IBIS Macromodel Task Group Meeting date: 09 July 2019 Members (asterisk for those attending): ANSYS: Dan Dvorscak Curtis Clark Cadence Design Systems: * Ambrish Varma Ken Willis Intel: Michael Mirmak Keysight Technologies: * Fangyi Rao Radek Biernacki Ming Yan Stephen Slater Maziar Farahmand Mentor, A Siemens Business: * Arpad Muranyi Micron Technology: * Randy Wolff Justin Butterfield SiSoft (Mathworks): Walter Katz * Mike LaBonte SPISim: * Wei-hsing Huang Teraspeed Labs: * Bob Ross The meeting was led by Arpad Muranyi. Mike LaBonte took the minutes. -------------------------------------------------------------------------------- Opens: - None ------------- Review of ARs: - Ambrish to produce a draft of BIRD197.4 incorporating NRZ_Threshold and DC_Offset clarifications. - Done - Randy to create a new [C Comp Model] BIRD draft incorporating the changes discussed in the meeting. - Done. -------------------------- Call for patent disclosure: - None. ------------------------- Review of Meeting Minutes: Arpad asked for any comments or corrections to the minutes of the July 2 meeting. Bob moved to approve the minutes. Randy seconded the motion. There were no objections. ------------- New Discussion: DDR5 related topics (bin list #11): Arpad asked if there were comments. Randy said he and Michael Mirmak were still researching. Complex C_comp modeling (bin list #6): Randy showed the draft BIRD. He said the only change was the insertion of a sentence to clarify that [C Comp Corner] could be ignored in non-driving mode. Arpad asked if it was ready for submission. Bob Ross moved to submit the BIRD to the Open Forum. Randy Wolff seconded. No one opposed, and the motion carried. Arpad will submit the BIRD. AR: Arpad Muranyi to submit [C Comp Corner] BIRD to Open Forum DC_Offset BIRD draft 197.4: Arpad showed a draft BIRD197.4 and an email from Fangyi Rao. Ambrish said BIRD197.4 had been drafted to clarify a few things. He noted that Fangyi had responded by email. There was confusion about if and when the model would change the waveform. Fangyi asked how the EDA tool would know if the waveform had been shifted by the model. Ambrish said the model would provide a threshold value indicating the amount of shift. Fangyi said the model could have both shifted and unshifted waveforms. He said the language was not completely clear that it was about the output waveform, not the input waveform. Arpad said the model could add its own offset even if it did not use the EDA tool value. Fangyi asked why we would shift the input waveform. Ambrish said it could be either input or output. Fangyi asked why we would need to know if it was shifted. Ambrish said it was to know not to shift it again. Fangyi said that was mixing two different things, DC offset and NRZ_Threshold were separate. He said it was confusing to use the input DC offset to shift the output. Ambrish said the model would choose how much it wants to shift, that it could ignore the DC offset. Fangyi said the model doesn't shift, it just processes the waveform. Arpad said we make the assumption is that GetWave output always would be centered around NRZ_Threshold, but Fangyi is saying it may not be. Ambrish disagreed, feeling that if there were differing DC offsets we would be doomed. Arpad said we might have an output that is not centered around the correct value. Fangyi asked how a shifted output could be physical. Ambrish said the model output waveform can be whatever it wants. Fangyi suggested the new sentences were not needed. He said it would help if DC_Offset was InOut. Arpad noted Walter and Fangyi were out on vacation at times when changes were made. Ambrish said he would be out the next few weeks. Fangyi said the threshold had to apply to the output waveform. Arpad noted that Walter Katz was the BIRD author, but Walter had indicated disapproval of some proposed changes. Maybe a new BIRD should be drafted. Ambrish asked if fixing the input vs. output waveform ambiguity would help. Fangyi pointed out the problematic sentence. Ambrish agreed that "input waveform" could cause confusion there. Fangyi asked why the output would be shifted by the input offset. Ambrish said the same offset applied at both ends. Fangyi asked who had suggested shifting the output waveform. Randy said it was a way of visualizing the actual waveform. Fangyi asked why the model would give the amount of shift. Ambrish felt it would be better for the model to do it, rather than provide the shift. Arpad said the output would be zero centered if DC offset equaled the threshold. When they are different the model gives the physical waveform. Fangyi said it was unnecessary. Ambrish said most models would not find a differing offset. Arpad agreed that we should not corner ourselves into an unlikely scenario. Ambrish said the model could still shift even if they were the same. Arpad said differing input and output offset precluded returning a zero centered waveform from the model. Ambrish agreed the model would have to shift, but he did not see that as a limitation. Fangyi just it should only be necessary to add the offset to the waveform. Arpad asked if it was InOut, would NRZ Threshold go away? Fangyi said it would still be needed/. Arpad again asked if a new BIRD was needed. He read portions of the BIRD draft, noted there was an ambiguity about "Rx pad". He said the definition should be improved for clarity about which Rx waveform we were talking about. Bob noted that 197.3 was introduced, but we probably would not agree on 197.4. Arpad said we should not take the BIRD out of Walter's hands, suggesting a new competing BIRD should be written. Bob said we should not have an early vote on BIRD197.3. Fangyi agreed to write a new BIRD. AR: Fangyi Rao to write new BIRD for DC offset. - Randy: Motion to adjourn. - Bob: Second. - Arpad: Thank you all for joining. ------------- Next meeting: 16 July 2019 12:00pm PT ------------- IBIS Interconnect SPICE Wish List: 1) Simulator directives