================================================================================ IBIS INTERCONNECT TASK GROUP http://www.ibis.org/interconnect_wip/ Mailing list: ibis-interconnect@freelists.org Archives at http://www.freelists.org/archive/ibis-interconn/ ================================================================================ Attendees from March 2, 2018 Meeting (* means attended at least using audio) ANSYS Curtis Clark Cadence Design Systems Bradley Brim Intel Corp. Michael Mirmak* Keysight Technologies Radek Biernacki* Mentor, A Siemens Business Arpad Muranyi* Micron Technology Justin Butterfield*, Randy Wolff* SiSoft Walter Katz*, Mike LaBonte* Teraspeed Labs Bob Ross* Michael Mirmak convened the meeting. No patents were declared. Justin Butterfield took minutes. Review of Minutes: - Michael called for review of the minutes from the February 28 meeting. Randy Wolff moved to approve the minutes. Mike LaBonte seconded. The minutes were approved without objection. Review of ARs: - Mike and Michael to look for missing meeting minutes. - Mike reported that he has not yet had time to look. Michael stated that he also has not had time to look. - Arpad Muranyi to draft a warning text when not using A_gnd as the reference terminal. - Arpad reported that he did send this out. Opens: - Arpad asked if we should spend time to clarify Radek's A_gnd changes. Michael agreed that we can add this to the agenda. - Radek Biernacki noted he sent some slides on referencing that he would like to go over. Arpad asked about the resistor example in these slides, and if it is a practical example, since S-parameters typically model transmission lines with time delay. Radek stated that the point of his examples is different, and the contents of the S-parameter models are not known. Also, it is possible to have external circuitry that effects how S-parameters function. - Bob Ross stated he has rail rules relaxation examples he would like to discuss. - Michael noted he has some updates from the IEEE P2401 discussion, but he will save this for the IBIS Open Forum. A_gnd Warning Text: Arpad showed the warning text he is proposing. The statement says that model makers should pay special attention to the Terminal_type for the reference node. He stated that using A_gnd is highly recommended. The first paragraph applies to File_TS. While, the second paragraph relates to Touchstone models inside IBIS-ISS subcircuits. However, this limitation does not apply if a reference for each port is applied. Radek thought the last sentence of the second paragraph is a given. Arpad noted he added this text to qualify the statements regarding a subcircuit that includes an S-parameter model. Bob asked if we are overreaching when talking about the contents of the IBIS-ISS subcircuits. Michael noted that we may need to think about where to put this text, since it is talking about both File_TS and IBIS-ISS. Arpad suggested to add the text with the other "Important" notes, but we can discuss this later. Michael asked if we have any disagreement about including Arpad's text. Radek stated that he is concerned the model maker should be free to do what they like in the IBIS-ISS subcircuit. The node 0 inside the IBIS-ISS subcircuit is also a concern. Bob agreed and noted that node 0 might not be brought out of the subcircuit. Arpad asked, given the issue with cascading models together, if it matters that the S-parameter is inside the IBIS-ISS subcircuit. Radek replied that we have that requirement, and it is okay. Arpad stated that his goal is to get model makers to think about how they are connecting the reference. Randy agreed that the warning should apply to both File_TS and IBIS-ISS cases. Bob commented that you could use references at each interface with IBIS-ISS. Arpad stated that his warning text notes this in the last sentence. Michael asked if we should include this text in draft18. Randy moved to include Arpad's reference warning text in BIRD189.5_draft18. Arpad seconded. There were no objections. Mike noted he made a stylistic change to reword the text and had sent this out over email. He changed the wording, but tried to retain the same meaning Arpad intended. He will send out one more email with a few more minor changes. Mike and Arpad can work on refining the A_gnd warning text offline [AR]. Rail Rules: Bob showed an example demonstrating his concerns with the rail rules. I/O signal rules are based on the one to one pin_name rule, but rails can have one to many pin to buffer connections. In his first example, he used bus_label to connect the rails. Each I/O model would need to reference the capacitance to somewhere. He did not include a full path rail model, but the Interconnect Model could include separate PDN models. In the second example, he included the full path of the PDN. In the first example, the rail terminals could be used as references and physical connections. In the second example, he would like to use more than one PDN model, but this is prohibited. Bob proposed relaxing this restriction to allow more than one bus_label. Also, if rails can connect to only one interface, it would be useful for decoupling only models to have a direct connection. A rail can appear at one interface, and we already imply this for Touchstone references. Michael asked what changes we would need to make to the BIRD document, and if we can simply delete these rules. Bob noted that for duplicate bus_labels we need to be careful that we apply this to only rails under a single Interconnect Model. Michael asked if Bob can take an AR to draft these changes to the rules. Bob commented that he did something similar already, but it was for Interconnect Model Group and not bus_label. Mike suggested for Bob to take the BIRD189.5_draft18_v2 and make his changes to the rail rules [AR]. Bob stated he can work on this. BIRD189.5_draft18_v2 Review: Arpad suggested to go through the rest of the changes from Radek in draft18. Michael asked about the comments on page 29. Radek noted that the word reference is still not resolved. Radek stated in the first Important note that we discussed removing the last sentence. Arpad agreed with this change. Michael noted this resolves several comments. Arpad asked about a comment on page 27 regarding A_gnd. He noted this sentence should say "a rail terminal or A_gnd". Michael noted there is a comment about the reference node for rails on page 28. Radek suggested that we need to cross-check this with BIRD158. Arpad noted he sent an email about Radek's changes. Michael asked if ATM is handling this issue since it is BIRD158 related. Arpad thought that BIRD158 did not need to change. Bob suggested that A_gnd should be used for BIRD158, as BIRD158 does not specify this. Arpad asked if this should be added as a note similar to the File_TS and IBIS-ISS referencing. Radek to draft text for referencing in BIRD158 [AR]. Next Meeting: The next meeting will be March 7. Arpad moved to adjourn. Mike seconded. The meeting adjourned without objection. Task List BIRD189.5 editorial additions/changes to be completed: