IBIS Macromodel Task Group Meeting date: 14 February 2023 Members (asterisk for those attending): Achronix Semiconductor: Hansel Dsilva Amazon: John Yan ANSYS: * Curtis Clark * Wei-hsing Huang Aurora Systems: * Dian Yang Cadence Design Systems: * Ambrish Varma Jared James Google: Hanfeng Wang GaWon Kim Intel: * Michael Mirmak * Kinger Cai Chi-te Chen Alaeddin Aydiner Keysight Technologies: Fangyi Rao Majid Ahadi Dolatsara Ming Yan Radek Biernacki Rui Yang Luminous Computing David Banas Marvell Steve Parker Mathworks (SiSoft): Walter Katz Mike LaBonte Micron Technology: * Randy Wolff Justin Butterfield Missouri S&T Chulsoon Hwang Yifan Ding Rivos Yansheng Wang SAE ITC Michael McNair Siemens EDA (Mentor): * Arpad Muranyi Teraspeed Labs: * Bob Ross Waymo: Zhiping Yang Zuken USA: Lance Wang The meeting was led by Arpad Muranyi. Curtis Clark took the minutes. -------------------------------------------------------------------------------- Opens: Arpad noted that he had added a new item to the agenda email: 9) AMI_GetWave block size with continually adapting models Arpad said he had asked about this topic in response to a DesignCon IBIS Summit presentation involving an adapting Rx AMI model. The specification currently says a model should work with any block size. The potential issue is that the block size controls the rate at which adaptation results can be returned in AMI_parameters_out. Adaptation results could appear with an artificial lag if the model settles faster than a single block of data, for example. Is this an issue we need to address? Randy, Michael and Kinger reported that attendance at DesignCon and the IBIS Summit seemed to be back to pre-pandemic levels. The show floor was full, and many presentations including the keynote presentation were full. IBIS's 30th anniversary was celebrated at IBIS Summit. ------------- Review of ARs: - Kinger to send out draft8 of the SPIM BIRD containing changes reviewed and discussed in the previous meeting. - Done. - Kinger to send out draft5 of the PSIJ Sensitivity BIRD containing changes incorporated from SPIM BIRD draft feedback. - Done. -------------------------- Call for patent disclosure: - None. ------------------------- Review of Meeting Minutes: Arpad asked for any comments or corrections to the minutes of the January 24th meeting. Randy moved to approve the minutes. Dian seconded the motion. There were no objections. -------------- New Discussion: Standard Power Integrity Model (SPIM) BIRD draft: Kinger reported that he had received feedback from Chi-te and Arpad in response to the draft8 he had sent out. He reviewed a work-in-progress draft 9 in which he was incorporating their changes. The Solution Requirements section was being rearranged in table form, per Arpad's suggestion. Arpad said the goal of Solution Requirements is to keep us focused on the problem being addressed. Randy agreed that the table form was important because this BIRD should adhere to the BIRD template. The BIRD is now relative to the newly approved IBIS 7.2. The sum of the weighting values of all stimulus ports equaling one was further explained to mean that the total current is normalized to 1.0A for AC impedance analysis. Kinger said for AC impedance analysis we normalize the overall current to 1.0A and distribute it according to the weighting values. Then, measuring the voltage at the observation port yields the impedance directly, because the total current is 1.0A. In the future, for transient analysis, the weighting values may be used as scaling multipliers to distribute the actual total current. The use of "Ball Grid Array (BGA) pins" was simplified to simply "pins" or "balls". The text now incorporates Arpad's suggestion to clarify that the N+M port model refers to the number of ports remaining after the VRM ports have been connected. Kinger revisited the section describing holistic platform PDN design and considering 3 major segments: on-die, package, and board. He said the SPIM modeling and Unified PI Target support all 3, but chip vendors will typically only provide target information for the package and board regions, which extend from DC to about 20MHz. This allows them to distribute models to platform vendors and protect their IP by not providing on-die target information. The last paragraph on page 6 started with, "For supporting DC analysis in the frequency domain,". Arpad and Randy said DC is really its own analysis type, and whether it might be an initial DC for a transient or frequency domain analysis is probably not important. Kinger agreed and removed "in the frequency domain." In that same paragraph, Kinger noted that language about terminals had caused some confusion. He said the point that was intended was that a PDN model provided in resistance network format to support DC IR analysis would contain terminals for every power and ground pin. For the S-parameter models provided for AC impedance analysis, however, power and ground pins would typically be grouped together into ports utilizing local ground references. The model maker would determine the port count of the S-parameter model based on a tradeoff between performance and accuracy. As a general comment, Arpad and Randy suggested that the Description sections of multiple keywords contained text that was better suited for Usage Rules. Randy said the Description should typically contain only one or two sentences. Kinger agreed and said the Description could be confined to a high-level definition and formatting, and the rest could move to Usage Rules. Arpad had an overall comment about end keywords, e.g., [End Device SPIM Group]. He said the language in the Required section wasn't quite sufficient, e.g. : Required: No. But it is required if a [Device SPIM Group] keyword is present. Arpad said end keywords are required to exist to match corresponding instances of start keywords, but they are illegal in any other situation. The existing language doesn't make the latter point. Randy said we should adopt whatever language is used for existing end keywords. For [End EMD Group] we use: Required: Yes, for each instance of the [EMD Group] keyword though the specification's language is not consistent across all keywords. Michael said Required was originally intended to mean that the keyword must exist in any valid IBIS file. He said we had never really standardized on the way to deal with dependency issues. Randy and Michael said we could leave this BIRD's language as is, and the Editorial task group can take up the overall issue throughout IBIS in the next version of the specification. Kinger said he would incorporate the changes discussed, wait a few days for any additional feedback on draft8, and then send out draft9 later in the week. Arpad again asked everyone to review the draft. - Ambrish: Motion to adjourn. - Curtis: Second. - Arpad: Thank you all for joining. AR: Kinger to send out draft9 of the SPIM BIRD containing changes reviewed and discussed in today's meeting. ------------- Next meeting: 21 February 2023 12:00pm PT ------------- IBIS Interconnect SPICE Wish List: 1) Simulator directives