Greg, The IBIS specification is intentionally silent about how to generate the impulse response for the channel, because there are different ways to do it, and EDA vendors might want to use their own "smarts" to do it the "best" way. You are correct, if someone wants to extract such an "ideal" IR, you would only make use of the C_comp and the impedance provided by the I-V curve from the analog model. BIRD 120 doesn't give any more detail (or restrictions) on how to generate the impulse response. So the EDA tool is free to do it the way they think it is the best to do it. I hope this helps, Arpad =========================================================== From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Gregory R Edlund Sent: Wednesday, July 11, 2012 9:15 AM To: 'IBIS-ATM'; ibis-macro-bounce@xxxxxxxxxxxxx Subject: [ibis-macro] Re: What part of Legacy IBIS is used by IBIS-AMI What if an EDA programmer wanted to discard the VT and ramp data and compute an "ideal mathematical" impulse response assuming a delta function? Is that allowed by BIRD 120? I took a quick look and didn't see anything specific about how to calculate the impulse response. In the "ideal mathematical" case, I would think all you need is C_Comp and some resistance extracted from the IV tables. Greg Edlund Senior Engineer Signal Integrity and System Timing IBM Systems & Technology Group 3605 Hwy. 52 N Bldg 050-3 Rochester, MN 55901 [Inactive hide details for "Walter Katz" ---07/11/2012 03:53:30 AM---I agree.]"Walter Katz" ---07/11/2012 03:53:30 AM---I agree. From: "Walter Katz" <wkatz@xxxxxxxxxx<mailto:wkatz@xxxxxxxxxx>> To: <Arpad_Muranyi@xxxxxxxxxx<mailto:Arpad_Muranyi@xxxxxxxxxx>>, "'IBIS-ATM'" <ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>> Date: 07/11/2012 03:53 AM Subject: [ibis-macro] Re: What part of Legacy IBIS is used by IBIS-AMI Sent by: ibis-macro-bounce@xxxxxxxxxxxxx<mailto:ibis-macro-bounce@xxxxxxxxxxxxx> ________________________________ I agree. Walter From: ibis-macro-bounce@xxxxxxxxxxxxx<mailto:ibis-macro-bounce@xxxxxxxxxxxxx> [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Muranyi, Arpad Sent: Tuesday, July 10, 2012 11:44 PM To: IBIS-ATM Subject: [ibis-macro] Re: What part of Legacy IBIS is used by IBIS-AMI That is correct. Arpad ================ From: ibis-macro-bounce@xxxxxxxxxxxxx<mailto:ibis-macro-bounce@xxxxxxxxxxxxx> [mailto:ibis-macro-bounce@xxxxxxxxxxxxx]<mailto:%5Bmailto:ibis-macro-bounce@xxxxxxxxxxxxx%5D> On Behalf Of Mirmak, Michael Sent: Tuesday, July 10, 2012 6:07 PM To: Walter Katz Cc: IBIS-ATM Subject: [ibis-macro] Re: What part of Legacy IBIS is used by IBIS-AMI Walter, Thank you! So, someone using IBIS-AMI models with valid traditional data in a workflow should expect changes in the IBIS TX C_comp or V-t (or [Ramp]) data to have an impact on the results provided by the receiver in an IBIS-AMI-based flow, assuming nothing else changes? - MM From: Walter Katz [mailto:wkatz@xxxxxxxxxx]<mailto:%5Bmailto:wkatz@xxxxxxxxxx%5D> Sent: Tuesday, July 10, 2012 12:20 PM To: Mirmak, Michael Cc: IBIS-ATM Subject: What part of Legacy IBIS is used by IBIS-AMI MM, The Legacy part of an IBIS model is used to generate the Impulse Response of the channel. One method of generating the impulse response is to do a step response, and take the derivative of the waveform at the Rx input. A simulator uses a combination of the Tx [Voltage Range], C_Comp, IV, VT and Ramp data, and the Rx C_Comp and IV data. Of course, [External Model] can also be used by a simulator. The following required Tx IBIS fields are not used in the AMI flow: Vmeas The following required Rx IBIS fields are not used in the AMI flow: Vinl Vinh Walter Walter Katz wkatz@xxxxxxxxxx<mailto:wkatz@xxxxxxxxxx> Phone 303.449-2308 Mobile 303.335-6156