IBIS Macromodel Task Group Meeting date: 04 June 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: Anyone willing to volunteer to take minutes? - Todd volunteered -------------------------- Call for patent disclosure: - None ------------- Review of ARs: - None ------------- New Discussion: Interconnect update: - Mike M. was not present, Arpad stated that EMD and BIRD 161 are being discussed. BIRD 156 Discussion: - Arpad: Still looking for closure based on last week's email - Does Rx sensitivity get used in the decision process? - Todd: Proposal is to use Rx_Receiver_Sensitivity as a hysteresis threshold - The signal has to go beyond to switch. - Arpad: Then the BIRD needs to include text to describe this? - Todd: Yes. - Ambrish: How is this used in the regular flow? - Fangyi: The simulator doesn't make a decision in the regular flow. - Ambrish: Why can't the model create the waveform for TX Getwave? - Why does the simulator have to sample at all? - Fangyi: This BIRD describes a retimer flow that requires the simulator to sample the waveform for retimers. - Ambrish: There should be text in the BIRD that describes how to model a retimer as a redriver. - Todd: That is a cookbook issue. - Fangyi: Agreed. - Fangyi: Can we still modify the BIRD text and vote on this for IBIS 6.0? - Arpad: We can make some changes, it depends on how complicated the changes get. - Radek: Even if the changes are larger than usual, we should be able to vote separately on accepting the changes. - Fangyi: I expect that the changes won't be more than a few sentences. - Arpad: Let's sort these changes out via email before Friday's meeting and have a clean revised version ready to show in the meeting. AR: Fangyi to get clarification of retimer flow ready for Friday. - Walter: SiSoft believes that voltage noise (Rx_Noise) associated with redriver devices can be modeled reliably and accurately. - We understand that standardization discussions will require more time than is available before the IBIS 6.0 specification closes. - We therefore agree with BIRD 156 as written, with the understanding that we can introduce and discuss a subsequent BIRD associating Rx_Noise with redrivers after IBIS 6.0 has been approved. BIRD 158 Discussion: - Radek: The common mode issue was set aside to talk about impulse responses. - Common mode can still use further clarification. - Walter: On the impulse response issue, legacy (non-Touchstone) models have a unit step control input. - BIRD 158 models still have a unit input, TX/RX gain can be represented either with a scaling element before/after the Touchstone models or within the S-parameter block itself. - Arpad: Legacy models have input voltages that are well understood. - But we need to be clear about where voltage scaling occurs for Touchstone data. - Is this done by the stimulus sources or in the Touchstone data? - We also need to be clear about initial conditions. - For instance, what is the 0 condition for Voh/Vol? - Radek: Step response is used to determine the impulse response. - If the initial conditions for the step response are correct, the resulting impulse response will be correct. - Fangyi: If everything is linear, the initial conditions don't matter. - Bob: The amplitude of the output is determined by the interaction between Tx_V, Tx_R and the S-parameter matrix. - The model maker needs to make sure the model is developed so all the pieces work together. - They can develop the model to use a unit step voltage if they want to. - Todd: That is correct. - Arpad: Is IBIS-ATM expected to make a recommendation on how these BIRDs should be voted for in Friday's meeting? - Bob: Not necessarily. - Radek: Do we need Voh/Vol on the transmitter? - Walter: Yes, to ensure proper biasing for the RX - Radek: The LTI approximation still applies, though. - You have assumed the whole network is LTI. - Todd: Yes, sometimes devices have limited areas of linear behavior and it's important to stay within that. - Ambrish: Do we need BIRD 158 at all? - Can't people just use BIRD 160? - Todd: BIRD 158 is a way to use S-parameters for the analog models using less text than BIRD 160 - Radek: That's true. BIRD 158 models are simpler. - Ambrish: How confident are we that this syntax won't change in the future? - Todd: On-die syntax hasn't changed in the last 4 years except for Tx_V and Tx_R, which were added to make the switch between unilateral and reciprocal S-parameter data simpler. BIRD 154 Discussion: - Arpad: Are there any outstanding issues or have the objections been resolved? - Bob: Yes, they are resolved. - It just requires that the parser handle the new syntax. ------------- IBIS Interconnect SPICE Wish List: 1) Simulator directives