IBIS Macromodel Task Group Meeting date: 14 March 2017 Members (asterisk for those attending): ANSYS: * Dan Dvorscak * Curtis Clark Broadcom (Avago): Xingdong Dai Bob Miller Cadence Design Systems: * Ambrish Varma Brad Brim Kumar Keshavan Ken Willis eASIC: David Banas Marc Kowalski Ericsson: Anders Ekholm GlobalFoundries: Steve Parker IBM Luis Armenta Trevor Timpane Intel: * Michael Mirmak Keysight Technologies: Fangyi Rao * Radek Biernacki Ming Yan Maxim Integrated Products: Hassan Rafat Mentor Graphics: John Angulo * Arpad Muranyi Vladimir Dmitriev-Zdorov Micron Technology: * Randy Wolff Justin Butterfield QLogic Corp.: James Zhou Andy Joy SiSoft: * Walter Katz Todd Westerhoff * Mike LaBonte Synopsys: Rita Horner Kevin Li Teraspeed Consulting Group: Scott McMorrow Teraspeed Labs: * Bob Ross TI: Alfred Chong The meeting was led by Arpad Muranyi. -------------------------------------------------------------------------------- Opens: - None. ------------- Review of ARs: - Walter to send an email to the ATM list containing the results of the straw poll on which BIRDs to include in the next revision. - Done. In addition, the topic was introduced and discussed at the Open Forum meeting on March 10th. -------------------------- Call for patent disclosure: - None. ------------------------- Review of Meeting Minutes: - Arpad: Does anyone have any comments or corrections? [none] - Dan: Motion to approve the minutes. - Mike L.: Second. - Arpad: Anyone opposed? [none] ------------- New Discussion: BIRD 187.3: - Michael M.: [sharing the latest revision of proposed text] - Discussion: The group reviewed the language Michael had proposed in response to Radek's comments about the "Increment" section in 187.2. Several changes were made including removing the incorrect statement that typ, min, and max values must be positive. The discussion also grew to include a general review of some of the AMI parameters language and whether things were stated clearly enough. In response to one suggestion that the exact intent of Range, Increment, etc., might not be clear enough, Radek suggested that we could add a general statement that these Formats that contain multiple values define the set of available values, from which one is chosen. There were also discussions about potential clarifications to List, Default, and others, though there was no consensus on whether any changes were necessary. Michael noted that BIRD 187 had already grown in scope from its original intent, and he did not want to take up any of the additional clarifications in BIRD 187. No one disagreed with this. Bob R. suggested that someone could write a different BIRD if they felt it necessary to rewrite this section. Walter suggested that the Editorial Task Group could take this up if they felt it necessary. He suggested that any language clarification, additional examples, etc., might not even require a BIRD. - Michael M.: I want to note that the only changes we are making to the current draft's text are: - Replacing the text in the "Increment" section with: The Increment Format, for Usage In and InOut, defines a set of discrete values not smaller than min and not larger than max, from which the user may select. Those values are defined in increments of delta with respect to typ, as typ + N*delta, where N is any integer (positive, negative, or zero) for which the value satisfies the expression min <= typ + N*delta <= max. The sign of delta shall be positive. The signs of typ, min, and max may be positive or negative and the values shall be min <= typ <= max. - Adding the following sentence at the end of the "Range" section: The signs of typ, min, and max may be positive or negative and the values shall be min <= typ <= max. - Arpad: This will be submitted to the Open Forum with these changes? - Michael M.: Yes, I'll make the changes and submit this as BIRD 187.3. Discussion precipitated by BIRD 158: - Walter: There has been a lengthy email discussion based on BIRD 158. - What does the model contain? - Where does it begin, and where does it end (the information in the Ts4file)? - Is there additional on-die interconnect? - Where is the package model? - I believe these same questions apply to the [External Model] approach and to what is in the [Model] in general. - General consensus has been that it goes up to the pad. - However, if you have something from Spice2IBIS, it may not include some of the on-die interconnect. - These questions are independent of Ts4file, and we need a general solution. - One suggestion is that for each of the models we specify what it includes. - I think it's reasonable to ask the model maker to specify. - Arpad: In IBIS we never expected the package model to be included in the [Model]. - We always assumed the on-die interconnect was included in the C_comp. - We assumed the [Model] just included the transistors in the buffer, and the C_comp was an inaccurate model of the on-die metal. The perspective of the [Model] terminals was the die pad. - Now BIRD 189 gives us a separate on-die interconnect. C_comp may not serve that same role anymore. I can see us wanting to distinguish. - Now that we have BIRD 189 we could just move all these concepts from the pad to the buffer terminal. - The [Model] terminals would now be the model's boundary, not necessarily the chip's boundary. - Instead of assuming it's the pad, it could now be on the die somewhere. - Walter: I think the default location should still be the pad. - I think it would be a mistake to change the default location. It would affect legacy models. - Bob R.: I agree that the original concept of on-die interconnect was zero impedance. - Due to the restrictions of IBIS, BIRD 158.3, and AMI, I don't think there's a way of connecting a Ts4file to an interconnect model. - Walter: We don't have to resolve it here. - I just want people to think about it. - Arpad: I think Walter and I agree completely except for the default boundary. - Walter: Yes, I think we agree that we need a way to specify. - Mike L.: Motion to adjourn. - Curtis: Second. - Arpad: Thank you all for joining. AR: Michael Mirmak to submit BIRD 187.3 to the Open Forum. ------------- Next meeting: 21 March 2017 12:00pm PT ------------- IBIS Interconnect SPICE Wish List: 1) Simulator directives