IBIS Macromodel Task Group Meeting date: 14 December 2010 Members (asterisk for those attending): Agilent: * Fangyi Rao * Radek Biernacki Ansoft: Chris Herrick Danil Kirsanov Ansys: * Samuel Mertens * Dan Dvorjak Deepak Ramaswamy * Jianhua Gu Cadence Design Systems: Terry Jernberg * Ambrish Varma Celsionix: Kellee Crisafulli Cisco Systems: * Mike LaBonte Stephen Scearce Ashwin Vasudevan Ericsson: * Anders Ekholm IBM: Greg Edlund Intel: * Michael Mirmak LSI Logic: Wenyi Jin Mentor Graphics: * John Angulo Vladimir Dmitriev-Zdorov Zhen Mu * Arpad Muranyi Micron Technology: Randy Wolff Nokia-Siemens Networks: * Eckhard Lenski Sigrity: Brad Brim Kumar Keshavan Ken Willis SiSoft: * Walter Katz Mike Steinberger * Todd Westerhoff ST Micro: Syed Sadeghi Teraspeed Consulting Group: * Scott McMorrow * Bob Ross TI: * Casey Morrison * Alfred Chong Vitesse Semiconductor: Eric Sweetman Xilinx: Mustansir Fanaswalla The meeting was lead by Arpad Muranyi ------------------------------------------------------------------------ Opens: - Arpad: We will next meet Dec 21 and Jan 4 - Ambrish and Radek can not join -------------------------- Call for patent disclosure: - none ------------- Review of ARs: - Arpad update Versions BIRD - Done - Arpad update Typos BIRD - Done ------------- New Discussion: Introduction of Jianhua Gu: - Working on AMI at Ansys Version BIRD discussion: - Arpad showed the latest draft - Arpad: There was a comment that an AMI file should not have higher version than the referencing IBIS - Bob: Any version should be allowed - That is why we want a separate Version keyword - Radek: The parser may handle the IBIS version but not the AMI - Arpad: Then the IBIS file should be updated - Radek: It can take a while to adopt new parsers - Walter: We are spending too much time on this - Mike: Can AMI_Version be IBIS_Version? - Bob: This is an AMI file, not an IBIS file - Arpad: The AMI spec could someday be separate - Arpad: There was a suggestion that no AMI_Version means 5.0 - Bob: That is my interpretation - I would oppose that - Radek: It should stay - Bob motioned to vote to submit this BIRD - Mike seconded the motion - Roll call vote: Agilent: yes Ansys: yes Cadence: yes Cisco: yes Ericsson: yes Intel: yes Intel: yes Mentor: yes Nokia: yes SiSoft: yes Teraspeed: yes TI: yes - The motion passed AR: Walter submit BIRD to open forum AR: Mike post BIRD to ATM website Arpad showed the Defaults BIRD: - Show how an "ffe" parameter converts to DLL string - Is the whole thing one parameter? - Fangyi: Names could be concatenated to form a namespace - For example AMI_RootName.ffe would be one parameter - Arpad: Anything InOut should be included in both In and Out strings - Reserved and Model_Specific will be removed - All others will be retained - Bob: Usage and Type are not passed - Arpad: These are not easy decisions - Walter: We don't need to debate this here - Ambrish: It be be just a recommendation, not a rule - Walter: Each vendor could make their own recommendations AR: Arpad update and distribute Defaults BIRD Walter showed a BIRD 122 sample SPICE deck: - This will handle both generic and BIRD 122 broadband models - The sample does not include Touchstone files - Colored text indicates what each part is used for - Fangyi: It is always 50 ohms? - Walter: That is common - Fangyi: In theory I can re-normalize - Radek: The termination should be defined separately - Walter: I will modify the BIRD to reflect comments - Anyone else can make suggestions by email - Bob: Is the s-param interchangeable with the parameterized circuit model? - Walter: With enough precision you should get the same results - But the reverse doesn't work - Fangyi: The Vt in the middle will not be in the s-param - Arpad: All DC elements will be lost - Scott: Unless you include Vt as a port - Bob: Should the model be adjusted to the voltage? - Arpad: Why such a small rise time in the PWL? - Walter: When you have Touchstone the rise time is zero - The Touchstone contains the rise time - Fangyi: Rise time can be excluded from the Touchstone - Walter: You could write that up for me - Bob: The rise time could be in the triangle buffers - Walter: You could write that up for me - Arpad: So Tr should be close to zero? - Walter: Yes - Bob: Why was S11 chosen as zero - Walter: A V source from the algorithmic model drives it - Kumar calls it a high impedance interface - Nothing reflects back from the control input - Scott: If S11 is zero, inside the model there is a terminator to ground - It is an isolation amp model - The AMI spec is explicit that it is high impedance, no termination to ground - Walter: Kumar should be asked about that - Scott: We need clear instruction on what is needed to stimulate the s-param - The transfer function depends on the ref impedance - Radek: It is not the ref impedance - Scott: We need to know what source impedance is required - Arpad: The circuit shows V sources driving it - Bob: Driver models are not meant to be cascaded - Fangyi: Do vendors have to provide this in their s4p? - Walter: The spec says those rows are not used - Fangyi: If the s4p has it the S11 will show up - Changing S12 will change the result - Radek: Agree - Walter: It depends on the simulator - Arpad: The question is what do we mean by "not used"? - Walter: I can't answer that - Mike Steinberger may be able to help - Radek: If there are S12 terms you will get a reflection - Walter: It would be the same of you made S11 V0 Walter showed an email from Fangyi: - Fangyi: The equation is at the bottom - Bob: We have defined S12 as zero - The real voltage gain is a function of S11 - Todd: Is this because S11 can affect V1 and therefore V2? - Fangyi: No - If V1 was fixed V2 would still be affected by S11 - Bob: The defaults should be zero for series impedances and infinity for impedances to ground. AR: Walter send example SPICE deck to Mike for posting ------------- Next meeting: 21 December 2010 12:00pm PT Next agenda: 1) BIRD 121-124 discussions ------------- IBIS Interconnect SPICE Wish List: 1) Simulator directives