IBIS Macromodel Task Group Meeting date: 22 Jan 2013 Members (asterisk for those attending): Agilent: Fangyi Rao * Radek Biernacki Altera: * David Banas Julia Liu Hazlina Ramly Andrew Joy Consulting: Andy Joy ANSYS: Samuel Mertens * Dan Dvorscak * Curtis Clark Steve Pytel Luis Armenta Arrow Electronics: Ian Dodd Cadence Design Systems: Terry Jernberg * Ambrish Varma Feras Al-Hawari Brad Brim Kumar Keshavan Ken Willis Cavium Networks: Johann Nittmann Celsionix: Kellee Crisafulli Cisco Systems: Ashwin Vasudevan Syed Huq Ericsson: Anders Ekholm IBM: Greg Edlund Intel: * Michael Mirmak Maxim Integrated Products: Mahbubul Bari Hassan Rafat Ron Olisar Mentor Graphics: * John Angulo Zhen Mu * Arpad Muranyi Vladimir Dmitriev-Zdorov Micron Technology: Randy Wolff Justin Butterfield NetLogic Microsystems: Ryan Couts Nokia-Siemens Networks: Eckhard Lenski QLogic Corp. * James Zhou 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 Ray Anderson The meeting was led by Arpad Muranyi ------------------------------------------------------------------------ Opens: - Arpad: Our next meeting will be Feb 5 -------------------------- Call for patent disclosure: - None ------------- Review of ARs: - None ------------- New Discussion: Interconnect Task Group report: - Michael M: - We went over David Banas' survey - Will meet tomorrow to for continued survey discussion & summit status report Arpad: Fangyi is not here for the scheduled discussion Discuss of survey results: - David: The results were: - Question 1: Which point in a serial communication link is the output of Tx GetWave() assumed to be representative of? - 7 chose A) The input to the analog channel. - 1 chose F) Other. (Please, explain below.) - Question 2: Is section 10 of IBIS v5.1 a normative part of the standard, which must be followed, or an informational appendix only, intended to provide one possible example of the AMI flow? - 6 chose Normative - 2 chose Informative, one was an EDA person - Section 10 is a normative standard that must be followed - Michael M: How many were model users? - David: - EDA 5 - IC 2 - Arpad: I responded Informative - Michael M: The survey is informative, but is it normative? - Does this say anything about inputs to GetWave and Init? - David: I don't think so - It would be good if someone else could look into this - In Init I convolve responses out of order - That should not matter, they are commutative - What is the point of being asked to change the point of my signal? - Once done with TX output, channel convolution is still the appropriate next step - Why is it different in the GetWave and non-GetWave cases? - James: Where does this come from? - David: From the number of A responses - Why does the difference between Init and GetWave exist? - Arpad: GetWave is not required - It needs to have a bit stream formed - James: Potentially the vendor can apply a portion of the TX to the channel response - In GetWave this has already been done - Walter: Historically there was an effort to make the TX and RX functions symmetric - We could have said the DLL Init returns just the equalization - The RX output would have been just the equalization - There was resistance to that - Someone said it was easier to generate the combined impulse response - For GetWave to be symmetric they need to add to an input impulse response - Symmetry was the key factor, all function add equalization to an input - James: The TX is ahead of the channel, but the RX is not - They are not symmetrical - David: No one answered "C" - Walter: Use_Init_Output required convolving GetWave with Init output - In one case you add just the channel response, in another Init output two - That caused double counting - Walter: One model maker had trouble putting a peaking filter in an RX - Non-LTI TX with some EQ in TX and RX gets very complicated - Requiring deconvolution was a problem - James; That is outside the scope of the 5.1 spec - Walter: That was in 5.0, now removed - James: You can't use both Init and GetWave in a simulation - Putting part of the response in each might not work - Ambrish: Some say we should always use GetWave - Init might replicate what GetWave does though - James: We have to tell the model maker what to do - Ambrish: To simplify the flow we had to eliminate that path - James: The old flow is not possible - Walter: That is right - This may be the only thing IBIS ever deprecated because it was unworkable - James: I don't see a way in 5.1 for the TX to choose settings - Walter: The idea was to open the eye at the RX - The TX could handle eye opening that 4 to 8 years ago, by normative rules - Specs gave eye opening requirements - At even 6Gb it no longer works - Opening the eye at the pin or pad harms the decision point signal - Now the RX has to handle eye opening optimization - James: In the field people need to know the right TX setting - Walter: That would be an informative rule, not normative - Backchannel systems send test patterns to find the optimum setting - James: The simulation must train, but it can take hours - Michael M: Can we have more surveying? - David's exercise has been very helpful - More questions need to be asked - Ambrish: The spec needs to say more about how things are done - James: I disagree - We do not have to say how things are done - We mostly have trouble knowing what to do - Walter: This can lead to Init-only RX models, leaving users stuck - James: Agree, users have a lot of frustration - The minimum requirement is the results have to come out the same - Being faster, etc. is optional James: We have divisions regarding analog models - These divisions are arbitrary - No matter where the division, TX plus channel has to give the same result - Arpad: If the dividing line moves we need a way to tell the tool ------------- Next meeting: 5 Feb 2013 12:00pm PT Next agenda: 1) Task list item discussions ------------- IBIS Interconnect SPICE Wish List: 1) Simulator directives