IBIS Macromodel Task Group Meeting date: 09 January 2024 Members (asterisk for those attending): Achronix Semiconductor: Hansel Dsilva Amazon: John Yan ANSYS: * Curtis Clark * Wei-hsing Huang Aurora System: * Dian Yang Raj Raghuram Cadence Design Systems: * Ambrish Varma Jared James Dassault Systemes: Longfei Bai Google: Hanfeng Wang GaWon Kim Intel: * Michael Mirmak Kinger Cai Chi-te Chen Liwei Zhao Alaeddin Aydiner Keysight Technologies: Fangyi Rao Majid Ahadi Dolatsara Stephen Slater Ming Yan Rui Yang Marvell: Steve Parker Mathworks (SiSoft): Walter Katz Graham Kus Micron Technology: Justin Butterfield Missouri S&T: Chulsoon Hwang Yifan Ding Zhiping Yang Rivos: Yansheng Wang SAE ITC: Michael McNair Siemens EDA (Mentor): * Arpad Muranyi * Randy Wolff Teraspeed Labs: * Bob Ross Zuken USA: Lance Wang The meeting was led by Arpad Muranyi. Curtis Clark took the minutes. -------------------------------------------------------------------------------- Opens: Arpad noted that the meeting scheduled for January 30th will be cancelled. January 30, 2024 (cancelled - DesignCon week) ------------- Review of ARs: Michael: Submit the AMI Test Data proposal to the Open Forum for introduction as an official BIRD. - Done. Submitted as BIRD229. Michael: Develop a full syntactically complete example demonstrating the AMI Test Data proposal. - In progress. -------------------------- Call for patent disclosure: - None. ------------------------- Review of Meeting Minutes: Arpad asked for any comments or corrections to the minutes of the December 19th meeting. Michael moved to approve the minutes. Ambrish seconded the motion. There were no objections. -------------- New Discussion: Cleanup of ATM email agenda items: Arpad initiated a review of the Topic bin list and Tabled topics. Topic bin list: Items 1 and 2 - Removing single ended-requirements for differential buffers: Michael said he would eventually handle these with a single BIRD. The group decided to leave them on the list. Item 3 - Digital signing of DLL/SO files: Michael said this was a question for other ATM attendees. Should we mention this topic in the specification or require signatures? Should the parser implement a test for this? Arpad, Bob, and Michael agreed that this topic could be taken up by the Quality task group instead. The group agreed to delete it from the ATM agenda. Tabled topics: 10) Modify C_comp for T-coil modeling Arpad suggested that we wait for more input from Walter. 11) Jitter HF/LF components and Jitter Amplification Michael said this topic was still relevant, but he had found it difficult to get technical consensus on how to proceed. Michael moved that we untable this topic and remove it from the list. Curtis seconded. There were no objections. 12) Other DDR5 related topics Arpad said this was a general topic for non-linear issues with DDR simulations. He said that EDA vendors may be using their own special techniques to deal with some of them. Michael observed that the specification never says anything about what should happen if you have a full set of non-linear I-V tables and V-t curves in an AMI model. So, it's already left to vendors to decide. Arpad said that in AMI we only have one set of channel impulse responses (including cross talk columns) that gets passed to AMI_Init. That could be enhanced by adding a second set, so we have rising and falling edge information. He said this wouldn't be a difficult change to make to the specification, and he wondered whether it would be worthwhile to add these multiple-edge techniques to the specification. Ambrish said he thought it was possible for this information to be captured in a single response. He said that prescribing the use of two different impulse responses was really prescribing one solution to the problem. Michael said that unless someone is actively asking for a solution, we should remove this item. Michael moved to untable the item and remove it. Bob seconded. There were no objections. 13) New BIRDs from Editorial Task Group? Bob suggested that we remove all 5 sub-headings of this topic. He noted that one attempt at addressing item e), BIRD181.1, had been rejected by the Open Forum. Bob said that the whole effort had gotten bogged down in an attempt to change the entire specification to use SPICE type V(node1, node2) voltage syntax. While this was technically the correct thing to do, it was burdensome to rewrite all of IBIS to address it everywhere. Bob moved to untable item 13 and remove it. Michael seconded. There were no objections. 14) How to handle missing min/max data? Arpad said he thought there was still an issue with the specification. Some parameters specify the use of typ if the min or max data is missing. Some parameters don't specify what to do, and in some cases it would not make sense to use typ data in lieu of min or max. However, he said this issue had been around forever, and he had never written a BIRD to address it. Michael asked whether there was a specific keyword that was particularly problematic. Arpad said he first ran into the issue when using I-V and V-t curves. The I-V and V-t usages would need to match. Their rules say to just use typ if min or max aren't available. However, what would we do if the I-V contained typ/min/max, but the V-t only contained typ? We would have a mismatch. There are loose ends like this that we should resolve. Arpad, Bob, and Ambrish agreed that we should leave this item on the list. Ambrish said he had recently had to refer to the specification to answer a customer question related to this issue. 15) AMI_GetWave block size with continually adapting models Arpad suggested that we keep this item on the list for now. 16) Multi-level analog buffer modeling (PAMn, C-phy, etc.) Arpad said this was not an urgent issue but a possible enhancement. He said he had run into this issue when trying to model multi-level signaling in a non-AMI simulation. He had implemented an [External Model] using Verilog-A, and he had wished a multi-level stimulus were available. Randy said that one of the possible solutions, adding support for a multi-level stimulus to multi-lingual IBIS models, might be a simple change. The group decided to leave this item on the list. 17) Updates on various PI related topics Arpad took an AR to ask Zhiping whether we need to keep this topic. AMI Test Data proposal: Michael reviewed several issues that he thought had caused of confusion or risked causing confusion with respect to BIRD229 and the existing IBIS 7.2 specification. Michael said that there is no formal definition of "block" in IBIS 7.2, though informally it refers to the block of data passed to each AMI_GetWave call, i.e., a block of waveform data whose number of samples is given by wave_size. Ambrish confirmed that one "block" of data contains the number of samples specified in wave_size. Michael said that when he had created his syntactically complete example by by modifying the original 2009 SiSoft AMI example, he had reduced the total amount of data processed by AMI_GetWave to minimize the size of the example files. He said that coincidentally, the total amount of waveform data processed in bits (1024 bits - 8192 samples in this 8 samples per bit case) happened to be the same as the number of samples in the impulse response passed to AMI_Init (1024 samples). Michael suggested that he should change the example, perhaps to 2048 bits worth of data processed by AMI_GetWave, to avoid any chance of confusing readers into thinking these quantities were related. Michael said he might propose a minor BIRD to clarify language related to block and block size. - Ambrish: Motion to adjourn. - Michael: Second. - Arpad: Thank you all for joining. New ARs: Arpad: Email Zhiping to ask whether he still plans to work on item 17 in the Tabled topics list, or whether we can remove it. ------------- Next meeting: 16 January 2024 12:00pm PT ------------- IBIS Interconnect SPICE Wish List: 1) Simulator directives