================================================================================ IBIS INTERCONNECT TASK GROUP Mailing list: ibis-interconnect@freelists.org ================================================================================ Attendees from March 15, 2023 Meeting (* means attended at least using audio) ANSYS Curtis Clark Intel Corp. Michael Mirmak* Michael Brownell Keysight Technologies Ming Yan Marvell Steve Parker MathWorks Walter Katz* Micron Technology Justin Butterfield* Randy Wolff* Siemens EDA Arpad Muranyi* ST Microelectronics Aurora Sanna Teraspeed Labs Bob Ross* University of Illinois Jose Schutt-Aine Zuken USA Lance Wang* 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 March 8, 2023 meeting. Michael displayed the minutes. Arpad Muranyi moved to approve the minutes. Randy Wolff seconded. The minutes were approved without objection. Review of ARs: - Michael to check if the Network Analyzer manuals documenting the original Touchstone can be posted to the IBIS website [AR]. - Michael received a response from the Keysight legal team. They had several questions, which he is working to answer. Michael suggested to keep this open. - Michael to ask the IEEE 370 group what is their preference for the direction of Touchstone and what features they would like to see [AR]. - Michael reported that he reached out to his contacts. He suggested to keep this open as a reminder to solicit more responses. - Arpad will send an email to the ATM reflector to ask about Touchstone 2. - Arpad reported this is done, but he did not get any responses yet. Opens: - Justin is not able to take minutes next week. Michael wondered if we could enable transcription in MS Teams in place of detailed minutes. - Michael noted that Steve Parker has worked through the backlog of documents to post on the website. Newer documents are not yet posted to the website. Discussion: Touchstone Direction Discussion: Michael asked if we have just not come up with the "killer app" feature in Touchstone for people to adopt it. He asked if that must have feature is on the bin list. The main feature for Touchstone 2 was the per port reference impedance. He noted mixed mode was also added. He asked if the reason Touchstone 2 is not more widely adopted in the industry is that there is not a lot of interest in these features. Arpad asked about the requirements that people don't like in Touchstone 2. Walter Katz replied the biggest requirement that caused issues for him was fixed mode vs. free mode. In an 's4p' file, there are 4 sets of complex numbers per row. In Touchstone 2 free mode, you can have wrapping of the numbers on multiple lines. Since parsers don't know the number of frequency points, this can cause issues when reading the data. Arpad commented that Walter’s proposal would like to make old parsers be able to read the new Touchstone format. He asked, if the new features require recalculating the data, how far can we go with the old parsers. Michael asked if there is no reason for people to update their parsers, since the new features do not present a compelling need to upgrade. Arpad replied that the per port reference impedance may not have been enough of an important feature. Walter commented, if we made an incremental change to Touchstone 1 to add the per port reference impedance, it would not effect other Touchstone parsers unless the per port reference impedance is needed. Having the per port reference impedance on the option line with multiple entries following the HSPICE format could allow for easier conversion between Touchstone 2 and Touchstone 1 styles. Then, Touchstone 2 could be enhanced to add the port mapping and other features. Bob Ross commented that the option line syntax can have the information in any order. Arpad agreed and noted there is a sentence about this in the Touchstone specification. Michael commented, from his discussions with users of Touchstone, users don't know about Touchstone 2. And, they are not compelled to upgrade based on their needs, since they tend to simulate SI and PI separately. Arpad noted that his tool does support Touchstone 2. Randy noted he does have models using Touchstone 2. Bob noted, at Teraspeed Labs, they mostly create and use Touchstone 1 files. Arpad reiterated his question of how far can we go with the old parsers. Michael replied it is not an issue to read in the Touchstone 2 data. The per port reference impedance is not needed from his side. The port mapping feature is interesting. But, the biggest feature being asked for is file size compression. Michael stated updating parsers is not a concern from his side, due to required periodic code reviews and updates. Randy stated that if we add the features that people need, then tools can be updated to support it. Walter proposed that we update Touchstone 1 to a Touchstone 1.1 or 1.2 to add the per port reference impedance using the HSPICE format. Then, we can work to update Touchstone 2 to add new features that can easily be down converted to Touchstone 1. Michael suggested to have a TSIRD to address this. He asked how does one identify an updated Touchstone file with this feature. Walter asked if we can get documentation on this format from Synopsys. Bob was also concerned how we would identify this format. Randy noted the only difference is the multiple entries after the R value. Michael will ask Synopsys if they have documentation on their per port reference impedance format that we can use in this discussion [AR]. Randy moved to adjourn. Arpad seconded. Next Meeting: The next meeting will be March 22, 2023. ================================================================================ Bin List: 1. Draft Touchstone document separating version 1.0 and 2.0 2. Encapsulating Touchstone 1.0 data 3. Touchstone 2.0 draft with TSIRD3 and TSIRD4 4. Pole-residue format 5. Port naming 6. Alternatives to the Touchstone 1.0 option line 7. Enable Cascading of S-parameters Through W-element 8. Touchstone 3.0 draft outline (dependent on several items above) Tabled ARs: - Arpad to give an example of the physical connectivity needed for EMD automation.