IBIS Macromodel Task Group Meeting date: 07 Feb 2011 Members (asterisk for those attending): Agilent: * Fangyi Rao * Radek Biernacki Altera: * David Banas Ansys: Samuel Mertens Dan Dvorscak Curtis Clark Arrow Electronics: Ian Dodd Cadence Design Systems: Terry Jernberg * Ambrish Varma * Feras Al-Hawari Celsionix: Kellee Crisafulli Cisco Systems: Ashwin Vasudevan Syed Huq Ericsson: Anders Ekholm IBM: Greg Edlund Intel: Michael Mirmak LSI Logic: Wenyi Jin Maxim Integrated Products: Mahbubul Bari Mentor Graphics: * John Angulo Zhen Mu * Arpad Muranyi Vladimir Dmitriev-Zdorov Micron Technology: * Randy Wolff NetLogic Microsystems: Ryan Couts Nokia-Siemens Networks: * Eckhard Lenski QLogic Corp. * James Zhou Sigrity: Brad Brim Kumar Keshavan * Ken Willis SiSoft: * Walter Katz Todd Westerhoff Doug Burns * Mike LaBonte Snowbush IP: Marcus Van Ierssel 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: -------------------------- Call for patent disclosure: - None ------------- Review of ARs: - None (may find some after review of minutes from last week) ------------- New Discussion: Analog BIRD discussion: - Arpad: We seem to be converging toward BIRDs 116 & 118 - We had a request to make BIRD 118 more general, not just for AMI - I will have a proposal for that next week - Arpad: We have slides about the boundary condition discussion started by Scott McMorrow - The thoughts and decisions documented in those slides will have to be incorporated in the specification, most likely BIRD 116 - We still need to discuss BIRDs 144 and 145. It would be best to separate the user defined corner idea out from BIRD 144 into BIRD 118 and discuss BIRD 144 as the direct connection of S-parameter models only - Walter: I would like to give my presentation intended for the summit - Ambrish: We can make termination changes for BIRD 144 - Feras: BIRD 144 allows for many corners - Arpad: We should take out the user defined corners from BIRD 144 and deal with it in BIRD 118 - Radek: We have discussed the slides about Scott's idea before - Unity gain amplifiers are not needed - Do we need to have BIRD 118 data in a separate file? - Arpad: I have changes in mind about that - The data could be at the bottom of the IBIS file, like package models - Bob: The parameter passing syntax is AMI specific - We should not be restricted to only AMI parameters - Arpad: We are talking about generalizing that in the next version of BIRD 118. Instead of a file name reference we could use the tree root name as a reference to the data. The data could be in the .ibs file or in an external file, just as it is done with the package modeling in IBIS. - Bob: BIRD 144 could also be generalized AR: Arpad propose method to generalize BIRD 118 Walter showed his email with a summary of the IBIS Summit presentations Walter showed his presentation intended for the summit but not shown there - Summaries of existing analog BIRDs - BIRD 122 overview - Pre-defined subcircuits - Walter added a D-A converter on slide 8 - Slide 10: Ambrish and Kumar added 50 ohm resistors to Touchstone output - Other vendors take different approaches - Slide 11: A new way to specify parameters would help - SiSoft supports using BIRDs 116 and 118 - Fangyi: Would like series R at Touchstone Tx output - Walter: With a value parameter that defaults to 0 - Ambrish: Do most vendors require this? - Feras: BIRD 116 is general, anything can go in the black box - Radek: What is the rationale behind the standardized subcircuit names? - Walter: SiSoft will supply subckt files with these names - Reserving a name prevents collision with other circuits using the same names - Ambrish: We have to deal with that issue every day - Radek: Usually you use directories to keep things separate - Walter: The problem is when they are in the same SPICE deck - Radek: Is there any rationale to the formation of the name "Thevenin"? - Walter: AMI because it is for AMI - Thevenin because it is equivalent to the actual circuits - Radek: Thevenin can apply to many kinds of circuits - Walter: I can come up with a more rational name - Bob: The circuits for these names must be defined - Feras: This is not a reserved name, just an example - Radek: The best approach is the ISS external model AR: Mike post Walter's updated presentation to ATM website Arpad showed one of the slides related to the discussion with Scott - Arpad: If ideal sources are used for the Tx D_to_A converter, the unity gain E elements are not needed - Radek: It should be up to the EDA vendor whether to include those - Fangyi: The E element is not the same as a short - Arpad: The circled "1" symbol in that drawing does not represent a short. It represents an infinite input impedance and zero output impedance unity gain ideal amplifier - Fangyi: The E element may confuse model developers - Arpad: Scott wants to insure the boundary condition is correct no matter what the EDA vendor does outside this model - We might simply write that into the spec - James: We should have matching impedance at the RX load end - Walter: Scott said E elements are not required when Touchstone is used - Arpad: But only if the Touchstone data incorporates the effects of the isolation amplifier. - Arpad: The general solution in BIRD 116 would be better - Deciding on hard-coded subcircuits is not working - Ambrish: There does not seem to be support for BIRD 144 - Bob: I support it - Arpad: We should handle this in two steps: - Modify BIRD 144 and remove the user defined corners (putting it into BIRD 118) - Then discuss BIRD 144 as the direct connected Touchstone proposal - Feras: This does not address the termination impedance - Bob: That is a reference impedance, not termination - Arpad: With [External Circuit] all ports are user defined and other [External Circuit]s can be connected to implement the port termination for the Touchstone [External Circuit] - With [External Model] the ports are all reserved port names and the port impedances are implemented by the EDA tool. In this case we have to define in the specification how the s-param model should be connected (terminated) in the EDA tool. - Feras: Agree - Bob: You just hook it up, there really is no issue - Arpad: It must be documented - Bob: We could standardize on 50 ohm reference impedance - Arpad: We can't have unwritten assumptions - The Touchstone model maker may have a different assumption than the EDA tool vendor's implementation (assumption) - Walter: To make BIRD 144 general we would have to specify that - Bob: S11 tells what the reference impedance is Meeting ended. ------------- Next meeting: 14 Feb 2011 12:00pm PT Next agenda: 1) Task list item discussions ------------- IBIS Interconnect SPICE Wish List: 1) Simulator directives