IBIS Macromodel Task Group Meeting date: 24 January 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 the meeting scheduled for January 31 was cancelled because of DesignCon. He asked whether we should also cancel the meeting on February 7th, as it's so close to DesignCon. Kinger suggested we cancel the meeting on the 7th, and he asked people to use the time to review the SPIM BIRD draft. There were no objections. - Status of regularly scheduled upcoming meetings: - January 31, 2023 - cancelled - week of DesignCon - February 7, 2023 - cancelled ------------- Review of ARs: - None. -------------------------- Call for patent disclosure: - None. ------------------------- Review of Meeting Minutes: Arpad asked for any comments or corrections to the minutes of the January 17th meeting. Kinger moved to approve the minutes. Ambrish seconded the motion. There were no objections. -------------- New Discussion: Standard Power Integrity Model (SPIM) BIRD draft: Kinger reported that he had met with Bob. Bob had updated the keyword hierarchy tree (section 3.3 of IBIS 7.1) with the new SPIM parameters. Bob had also suggested some formatting cleanup in the example for [Device SPIM Group]. Arpad noted that the Solution Requirements section is a separate section of the BIRD explaining the end goal, but it does not belong in the Proposed Changes to be incorporated in the specification. Kinger said he would send out a draft8 incorporating Bob's changes and addressing Arpad's comment. Arpad and Kinger asked everyone to carefully review the draft and provide feedback. PSIJ Sensitivity BIRD draft: Kinger reported that he had created a new draft by incorporating relevant suggestions he had received for the SPIM BIRD draft, per Arpad's suggestion at the previous meeting. Kinger said he would send out draft5 after the meeting. Multi-level analog buffer modeling (PAMn, C-phy, etc.): Arpad previewed a presentation he will be giving at the DesignCon IBIS Summit on Friday, February 3, 2023. He noted that IBIS 6.1 introduced support for PAM4, and IBIS 7.2 will support PAMn, but only in the AMI context. He said there are scenarios for which supporting multi-level signaling with conventional analog IBIS [Model]s would be beneficial, and he referred to a previous GDDR6X presentation: https://urldefense.proofpoint.com/v2/url?u=https-3A__ibis.org_summits_aug21b_wolff2.pdf&d=DwIGAg&c=nKjWec2b6R0mOyPaz7xtfQ&r=DcQR-qLpQg5lIreuM6-NYECRIAFXt268PRNS5WO043M&m=CVNFfzBskqJ0L9vcmQNqZrw_cV5Kz7_kM6tDxcv9O-3h1WL0CUUDVja8RWZlrz2Z&s=7sKZGGaYP0bQrSuTksQkvNwjD94svUju8KLQ5ucaow8&e= Arpad said that extending the traditional I-T, V-t, K(t) algorithms to support multi-level signaling would not be too difficult. The difficulties might lie in the logistics of interactions with other keywords. Arpad mentioned [Driver Schedule] as an example of such a keyword. Arpad noted that Randy had suggested that a minimal solution might be to extend IBIS by adding a multi-level stimulus for use only with multi-lingual models. Arpad suggested that instead of the currently defined '0', '1', and 'X' states, we might allow an integer value to represent the various states. He said one complication might be the A_D and D_A converters defined for multi-lingual models, but he suggested a simple linear equation of the form: V = k * (stimulus_index) + c might be sufficient to represent the voltage for each stimulus level. Bob asked if this was intended to work for the true differential modeling supported by [External Model]. Arpad said he thought it would. He said the existing true differential models still take a single value to represent the stimulus. Arpad said the pseudo-differential models might encounter an extra complication. Currently, we expect one [Model] to get the stimulus and the other [Model] to get the inverted stimulus. We might have to decide how this would work for a multi-level stimulus, but he said these are details we could work out later. Walter said he had concerns about a solution that only supported multi-lingual models. He said he wasn't sure anyone would need to model these devices outside the AMI context, but if we were to enhance conventional analog IBIS [Model]s, he would prefer something that a SPICE engine could support. Walter suggested a simple model based on a lab measurement scenario. He said you might connect a PAMn device to a 50 Ohm load to ground, put the device in each of the n states, wait for it to settle, and measure the voltage and impedance of the device at steady state. You would end up with a table of the impedance of the device at each of the levels. You could add in legacy power and ground clamp tables, and have the model maker define some effective K(t) rise/fall time curves for the transitions from state to state, and you'd end up with a simple and effective model that is easy for EDA tools to implement. You could define an algebraic way to extend such a basic table model to handle non-linear regions. Alternatively, Walter suggested that you could extend a typical [Model] set of active device I/V curves to 4 curves (for a PAM4 example) and define a set of K(t)s that describe how you switch from one state to another. Arpad said these were interesting suggestions. However, he said that we will need an expanded stimulus definition regardless of how we choose to implement the multi-level model. Arpad said he thought we could consider the expanded stimulus definition and the multi-level modeling as separate BIRDs. - Walter: Motion to adjourn. - Curtis: Second. - Arpad: Thank you all for joining. AR: Kinger to send out draft8 of the SPIM BIRD containing changes reviewed and discussed in today's meeting. AR: Kinger to send out draft5 of the PSIJ Sensitivity BIRD containing changes incorporated from SPIM BIRD draft feedback. ------------- Next meeting: 14 February 2023 12:00pm PT ------------- IBIS Interconnect SPICE Wish List: 1) Simulator directives