IBIS Macromodel Task Group Meeting date: 14 November 2023 Members (asterisk for those attending): Achronix Semiconductor: Hansel Dsilva Amazon: John Yan ANSYS: * Curtis Clark * Wei-hsing Huang Aurora System: Dian Yang Cadence Design Systems: Ambrish Varma Jared James 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: Curtis noted that the meeting scheduled for November 7th had been cancelled. Arpad reviewed the schedule of upcoming meetings. The group decided to cancel the following meetings: November 21, 2023 December 26, 2023 January 02, 2024 ------------- Review of ARs: Kinger: Prepare some slides to aid in the discussion of BIRD220 and BIRD226 and their interaction - Done. See discussion below. Michael: Ask Alaeddin to submit his Ignore Block proposal to the Open Forum as an official BIRD - Done. Alaeddin said he would submit his proposal to the Open Forum. Michael: Send out draft15 of the AMI Test Data proposal including more feedback from the ATM meeting. - Done. 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 October 31st meeting. Michael moved to approve the minutes. Kinger seconded the motion. There were no objections. -------------- New Discussion: BIRD220 and BIRD226: Kinger reviewed his slide presentation on the interaction between BIRD220 and BIRD226, which he had sent to the ATM list prior to the meeting. He noted that the slides were not intended to go into details about the individual BIRDs. Instead, his goal was to explore high level scenarios and what the two BIRDs were able to handle. Kinger said that platform PDN design is complicated. There may be multiple power rails for a given interface, and a single rail may provide power to multiple buffers. It is common to attempt to consolidate power rails for cost tradeoff reasons. He said it is necessary at a system level to consider the PSIJ contributions from all rails. slide 3 - BIRD220 Kinger said that BIRD220 is applicable to a scenario with a single power rail providing power to a single buffer. He asked whether it could handle one rail to many buffers, or many rails to one buffer. He also asked whether BIRD220 would supersede the [ISSO PU] and [ISSO PD] keywords and whether there would be double counting of effects if both were used. Randy said BIRD220 could handle the one rail to many buffers scenario. If your PDN model allows you to see the rail voltage output at each buffer, then you could instantiate multiple instances of the buffer [Model] to connect to them. Arpad addressed the multiple rails to one buffer scenario. He said that it is a fundamental limit of the existing IBIS [Model] keyword that it only considers one voltage rail. He said that with [Model], which is what BIRD220 enhances, it would be difficult to address the case where a buffer requires multiple power rails. He noted, however, that [External Circuit] is not limited in terms of how many terminals it can use. With an [External Circuit], separate supply rail terminals for multiple Vdd rails could be provided. One could then model IBIS buffers with more than just an output stage supply rail. Randy, Arpad and Yifan confirmed that BIRD220 and the [ISSO PU] and [ISSO PD] keywords are complementary and do not result in double counting. Both are necessary to improving the correlation between an IBIS buffer [Model] simulation and a full transistor level SPICE simulation. The ISSO keywords characterize the final stage and modulate the drain to source current based on the VDDQ voltage. They modulate the drive strength and therefore the edge rate. BIRD220 characterizes the delay sensitivity in the predriver and shifts the location of the edge in response to changes in VDD. Arpad asked whether BIRD220 and BIRD226 would result in double counting of PSIJ effects. If an IBIS [Model] containing BIRD220 information were used as part of a BIRD226 type system simulation, would there be double counting? Kinger said there would not be double counting. Because BIRD226 envisions an initial SI simulation done with ideal power, there would be no variation in VDDQ, and BIRD220 would have no effect. Kinger said he thought BIRD220 and BIRD226 were complementary and could co-exist without fear of double counting. Arpad and Randy said their team had started reviewing BIRD220 with an eye toward implementation. They said they had some questions from the development team including: - How do BIRD220's K(t) equations interact with the ISSO keywords? - Is there a simpler approach involving shifting the original K(t) as opposed to the new A and B terms introduced into the equation in BIRD220? Randy said they would send Chulsoon and Yifan detailed questions offline, and he and Arpad asked other EDA vendors to review BIRD220 with implementation in mind. Chulsoon and Yifan said they would be happy to discuss any feedback on BIRD220. Arpad noted that the IBIS Open Forum had asked this group to review BIRD220 and BIRD226 to ascertain their readiness for a vote. Arpad said he thought BIRD226 might be ready for a vote. Arpad suggested that we hold off on proposing a vote on BIRD220 in the Open Forum until we have had a chance to discuss the new feedback/questions. - Curtis: Motion to adjourn. - Kinger: Second. - Arpad: Thank you all for joining. New ARs: - None. ------------- Next meeting: 28 November 2023 12:00pm PT ------------- IBIS Interconnect SPICE Wish List: 1) Simulator directives