Todd, I was thinking about writing a patent for an anti-gravity device, but now you talked me out of it! Greg Edlund Senior Engineer Signal Integrity and System Timing IBM Systems & Technology Group 3605 Hwy. 52 N Bldg 050-3 Rochester, MN 55901 From: "Todd Westerhoff" <twesterh@xxxxxxxxxx> To: Gregory R Edlund/Rochester/IBM@IBMUS Cc: <ibis-macro@xxxxxxxxxxxxx> Date: 12/12/2012 01:12 PM Subject: [ibis-macro] Re: Analog Buffer Model Inside DLL Sent by: ibis-macro-bounce@xxxxxxxxxxxxx Greg, Ask yourself how the person writing an algorithmic model should accurately model the reflections associated with an unspecified channel. If there’s a way to do that, I’d like to hear about it. Todd. Todd Westerhoff VP, Software Products Signal Integrity Software Inc. • www.sisoft.com 6 Clock Tower Place • Suite 250 • Maynard, MA 01754 (978) 461-0449 x24 • twesterh@xxxxxxxxxx “I want to live like that” -Sidewalk Prophets From: Gregory R Edlund [mailto:gedlund@xxxxxxxxxx] Sent: Wednesday, December 12, 2012 1:41 PM To: Todd Westerhoff Cc: ibis-macro@xxxxxxxxxxxxx Subject: Re: [ibis-macro] Analog Buffer Model Inside DLL Todd, Thanks for the response. So, there are no "mathematical tricks" one can play in the DLL to account for the absence of the analog buffer model in the impulse response? You can tell I haven't taken enough time to think this through all the way. I'm having a knee-jerk reaction to a discussion that's going on internally. 8-) I'm about to dig into the IBIS 5.1 flow material to support my position. I just wanted to make sure I had my ducks in a row and get some outside corroboration. Anyone else care to chime in? 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 Todd Westerhoff ---12/12/2012 12:31:11 PM---Greg, That is not possible. The analog model, by definitiTodd Westerhoff ---12/12/2012 12:31:11 PM---Greg, That is not possible. The analog model, by definition, interacts with the channel and must be From: Todd Westerhoff <twesterh@xxxxxxxxxx> To: Gregory R Edlund/Rochester/IBM@IBMUS Cc: "ibis-macro@xxxxxxxxxxxxx" <ibis-macro@xxxxxxxxxxxxx> Date: 12/12/2012 12:31 PM Subject: Re: [ibis-macro] Analog Buffer Model Inside DLL Greg, That is not possible. The analog model, by definition, interacts with the channel and must be included in the impulse response. The equalization, also by definition, is considered to be electrically isolated from the channel and is thus represented in the DLL. Putting the analog model in the DLL violates a fundamental assumption of IBIS-AMI. You may get good-looking results, but they will be invalid. Todd. -- Todd Westerhoff VP, Software Products SiSoft 6 Clock Tower Place, Suite 250 Maynard, MA 01754 (978) 461-0449 x24 twesterh@xxxxxxxxxx www.sisoft.com “I want to live like that" -Sidewalk Prophets On Dec 12, 2012, at 1:13 PM, Gregory R Edlund <gedlund@xxxxxxxxxx> wrote: What nasty things are likely to happen if someone puts the analog buffer model inside the DLL? At the very least, the impulse response will be incorrect. Are there any circumstances under which this can work correctly? Greg Edlund Senior Engineer Signal Integrity and System Timing IBM Systems & Technology Group 3605 Hwy. 52 N Bldg 050-3 Rochester, MN 55901