IBIS Macromodel Task Group Meeting date: 29 September 2009 Members (asterisk for those attending): Adge Hawes, IBM Ambrish Varma, Cadence Design Systems * Anders Ekholm, Ericsson * Arpad Muranyi, Mentor Graphics Corp. Barry Katz, SiSoft * Bob Ross, Teraspeed Consulting Group Brad Brim, Sigrity Brad Griffin, Cadence Design Systems Chris McGrath, Synopsys * Daniel Kirsanov, Ansoft David Banas, Xilinx Deepak Ramaswany, Ansoft Donald Telian, consultant Doug White, Cisco Systems Eckhard Lenski, Nokia-Siemens Networks Essaid Bensoudane, ST Microelectronics * Fangyi Rao, Agilent Ganesh Narayanaswamy, ST Micro Gang Kang, Sigrity Hemant Shah, Cadence Design Systems Ian Dodd, consultant Jerry Chuang, Xilinx Joe Abler, IBM John Angulo, Mentor Graphics John Shields, Mentor Graphics Ken Willis, Cadence Design Systems Kumar Keshavan, Sigrity Lance Wang, Cadence Design Systems Luis Boluna, Cisco Systems * Michael Mirmak, Intel Corp. * Mike LaBonte, Cisco Systems Mike Steinberger, SiSoft Mustansir Fanaswalla, Xilinx Patrick O'Halloran, Tiburon Design Automation Paul Fernando, NCSU Pavani Jella, TI Radek Biernacki, Agilent (EESof) * Randy Wolff, Micron Technology Ray Komow, Cadence Design Systems Richard Mellitz, Intel Richard Ward, Texas Instruments Samuel Mertens, Ansoft Sam Chitwood, Sigrity Sanjeev Gupta, Agilent Shangli Wu, Cadence Design Systems Sid Singh, Extreme Networks Stephen Scearce, Cisco Systems * Steve Pytel, Ansoft Syed Huq, Cisco Systems Syed Sadeghi, ST Micro Ted Mido, Synopsys * Terry Jernberg, Cadence Design Systems * Todd Westerhoff, SiSoft * Vladimir Dmitriev-Zdorov, Mentor Graphics Vikas Gupta, Xilinx Vuk Borich, Agilent * Walter Katz, SiSoft Zhen Mu, Mentor Graphics ------------------------------------------------------------------------ Opens: - Mike L said he needs to get caught up on posting meeting minutes - Arpad: What should EDA tools do with parameter_string_out? - Walter: OUT or INOUT can be on any model-specific parameter - Reserved parameters can be INFO - Fangyi: How does the tool use model-specific parameters? - Walter: For example, if tap_coeff is OUT, the model will return the value - Fangyi: But the name may not be the same in all tools - Walter: We discussed this 2 years ago - New parameters are bound to appear - If they are published, other vendors could adopt the same names - Then they could become reserved parameters - Fangyi: The EDA tool should only observe reserved parameters - What does the specification imply the tools should do? - Todd: Nothing - Arpad: Would like to discuss: - List of new BIRDs - What is needed to release IBIS-ISS?: -------------------------- Call for patent disclosure: - No one declared a patent. ------------- Review of ARs: - Mike change web page to make items easily linkable - Arpad dropped this from the AR list - Arpad Write a clarification BIRD to discuss accuracy issues related to the various AMI clock_tick algorithms in an IBIS-AMI DLL - TBD - Todd: Update the BIRD for IBIS S-parameter box based on feedback from discussion - No update - Arpad: Write parameter passing syntax proposal (BIRD draft) for *-AMS models in IBIS that is consistent with the parameter passing syntax of the AMI models - TBD - TBD: Propose a parameter passing syntax for the SPICE - [External ...] also? - TBD - Arpad: Review the documentation (annotation) in the macro libraries. - Deferred until a demand arises or we have nothing else to do ------------- New Discussion: Walter's AMI proposal: - Fangyi: PMC has reservations about the new flow - They are trying to do statistical analysis - They add DFE to the impulse by simple addition - Assuming Init includes DFE breaks their flow - The have to convolve, not add - Walter: Tx_Init_Returns_Filter option can be set to do it the old way - Vladimir: This flow is good because it corresponds to a physical process - It has the flexibility to control if convolution is used - There should be a different flow if there is crosstalk noise - Walter: So sometimes it would be better to convolve inside Init so EDA tool doesn't have to - But that makes it difficult to process for noise - For this the filter should be an input to Tx_Init - Vladimir: The question is about GetWave - We combine 3 responses into one for performance - But for crosstalk we can't combine them - Walter: Tx_Use_Init_Output is flawed, and should be false - We should let Tx_GetWave do the convolution, instead of EDA tool - Arpad: Is that a new flow? - Walter: No, the option parameters allow it now - Tx_Use_Init_Output = false - When you call Tx_GetWave it has the filter impulse response - This is what the dotted line represents - Arpad: I did not expect the dotted line to mean that - Walter: The DLL saves it in memory - Cadence did not want to convolve inside GetWave - They wanted an overlap and save method - Fangyi: You suggest Init should never modify the impulse response - Walter: Init returns the modified Response - But it also has it in memory - Fangyi: The specification says RX_Init can modify the impulse response - Walter: That was a fundamental error - We said 2 years ago that would break the crosstalk flow - The new proposal fixes that - Fangyi: The digital input can be recovered? - Walter: Yes - Fangyi: The Rx has to process only the main channel, not crosstalk - That breaks the flow - The proposed new flow is cleaner - Arpad: I just modified the presentation to reflect what we have discussed - Fangyi: We need to settle the -0.5 to +0.5 or 0 to 1 question - Walter: It is -0.5 to +0.5 - Transitions occur nominally at 0 - Putting the old flow through a lossless channel results in -0.5 to +0.5 output - Vladimir: The point is that the magnitude has to be 1 - Fangyi: The DC bias is important - Vladimir: Can the specification be simplified? - Did IC vendors require all these options? - Walter: We could deprecate the old modes in 5.1 - Arpad show IBIS 5 page 188 that says samples are "centered around zero" - Arpad: If we eliminate the convolution options can the arrows go away? - Walter: They can go away - Arpad corrected math expressions for the Tx_GetWave and Rx_GetWave outputs - Walter: If Tx_GetWave is missing it must be replaced with a convolution - Arpad: I will clean this up and Mike L will post it Walter showed an outline of AMI documentation - The string format was an error and should be deprecated - Table has been a problem - We will want to make some model_specific params reserved - They should be deprecated - We should support env vars - We should support vectors, labels, scale, and limit - There should be naming rules for parameter leafs - Propose new reserved params: - published - tstonefile - true_diff_analog_model - Computed parameters: - Some tools support more than 3 corners - A language like Perl with if/else might do it - It will take a compromise of EDA vendors - We should make many modifications in one block - Walter could modify the IBIS specification with these changes - Arpad: We should discuss it before it goes to the Open Forum - Walter: We should have a small EDA vendor subcommittee for this - Walter, Arpad, Fangyi, ... - Bob: It has to be open to anyone - Want to see 6 vendors participate - Bob: There should be no need to deprecate - Walter: The EDA vendors should decide that AR: Walter email Arpad on status of proposed AMI specification rework Next meeting: 06 Oct 2009 12:00pm PT -------- IBIS Interconnect SPICE Wish List: 1) Simulator directives