Arpad, In statistical simulations with models that support backchannel in time domain, the user must set the Tx Tap coefficients. Backchannel is totally compliant with BIRD 120.1 flows. The only difference is that the EDA tool applies the backchannel portal to each Tx/Rx pair in the crosstalk simulation. Walter -----Original Message----- From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Muranyi, Arpad Sent: Tuesday, August 23, 2011 1:08 PM To: ibis-macro@xxxxxxxxxxxxx Subject: [ibis-macro] Re: Backchannel and the crosstalk simulation flow Walter, I understand that backchannel is all time domain. The point I am trying to make is that a model which supports backchannel should probably not even modify the IR at all in AMI_Init. The only reason this could be useful is for FD simulations, but since the coefficients are not set up yet at the time the AMI_Init function is executed (since backchannel training comes later in GetWave), I don't see how modifying the IR in AMI_Init could give correct results. The other part of my question is whether we should say something in the spec about the crosstalk and backchannel flow in our time domain flow descriptions. Does everyone know what to do the way this flow is described today in BIRD 120.1? Thanks, Arpad ============================================================ -----Original Message----- From: Walter Katz [mailto:wkatz@xxxxxxxxxx] Sent: Tuesday, August 23, 2011 11:41 AM To: Muranyi, Arpad; ibis-macro@xxxxxxxxxxxxx Subject: RE: [ibis-macro] Backchannel and the crosstalk simulation flow Arpad, Backchannel is time domain, which does not use the modified impulse response from the AMI_Init function. Since Tx_GetWave is responsible for applying the Tx equalization, then backchannel with crosstalk will just work. This would be very complicated if Use_Init_Output was not deprecated. Walter -----Original Message----- From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Muranyi, Arpad Sent: Tuesday, August 23, 2011 12:30 PM To: ibis-macro@xxxxxxxxxxxxx Subject: [ibis-macro] Backchannel and the crosstalk simulation flow Hello everyone, I took an AR last week to start this thread with a few questions on how the backchannel communication proposal would affect the existing AMI crosstalk flow. Summary of the crosstalk flow: =============================== 1) The Tx tap settings of all aggressors and the victim channel are determined from normal through channel simulations. 2) The AMI_Init functions of the aggressor Tx models will be used to modify the crosstalk impulse response on the victim channel. 3) The AMI_Init function of the victim Tx model will be used to modify the through impulse response on the victim channel. 4) The Rx model will further process the modified impulse responses in its AMI_Init and AMI_GetWave functions. Note that in case the Tx models do not modify the impulse response in their AMI_Init function, or their AMI_GetWave function have a glorified version of the algorithm in their AMI_Init function, the EDA tool will have to use the GetWave functions of the Tx models on the time domain waveform to get the correct crosstalk response. Summary of the Backchannel flow: ================================ The communication between the Tx and Rx GetWave functions establish the settings of the various coefficients for the Tx model. Note that this is done in the GetWave functions, and the AMI_Init function will not be executed after the backchannel communication finished. Questions: ========== 1) Backchannel simulations render the AMI Init function unusable for modifying the impulse response(s) of the channel. Should we have a rule that in this case the model shall not return a modified impulse response in the AMI_Init function? 2) The crosstalk flow relies on the AMI_Init function's modification of the crosstalk (and through) impulse responses. The outcome of the backchannel communication is not known at this time. How are we going to incorporate the results of the training in the crosstalk simulations? Again, should we have a rule that in this case the model shall not return a modified impulse response in the AMI_Init function? 3) In case the aggressor's AMI_Init function does not modify the crosstalk impulse responses, the EDA tool needs to use the time domain waveforms and use the time domain flow to figure out the crosstalk effects. Our spec and BIRDs do not describe the time domain flow for crosstalk simulations. BIRD 130 (Crosstalk BIRD) was written to clarify the rule about the Tx model modifying the crosstalk impulse responses. We did not write anything on how crosstalk is done in the time domain. Adding the backchannel communication to the flow, I wonder if we should address these in a more detailed time domain flow. Is our current time domain flow description adequate for any EDA vendor and model maker to know how to implement these features in the tools and models? There may be more questions, but these might get some discussions going... Thanks, Arpad ===================================================================== --------------------------------------------------------------------- IBIS Macro website : http://www.eda.org/pub/ibis/macromodel_wip/ IBIS Macro reflector: //www.freelists.org/list/ibis-macro To unsubscribe send an email: To: ibis-macro-request@xxxxxxxxxxxxx Subject: unsubscribe --------------------------------------------------------------------- IBIS Macro website : http://www.eda.org/pub/ibis/macromodel_wip/ IBIS Macro reflector: //www.freelists.org/list/ibis-macro To unsubscribe send an email: To: ibis-macro-request@xxxxxxxxxxxxx Subject: unsubscribe --------------------------------------------------------------------- IBIS Macro website : http://www.eda.org/pub/ibis/macromodel_wip/ IBIS Macro reflector: //www.freelists.org/list/ibis-macro To unsubscribe send an email: To: ibis-macro-request@xxxxxxxxxxxxx Subject: unsubscribe