[ibis-macro] Re: Analog Buffer Model Inside DLL

  • From: Gregory R Edlund <gedlund@xxxxxxxxxx>
  • To: Todd Westerhoff <twesterh@xxxxxxxxxx>
  • Date: Wed, 12 Dec 2012 12:41:28 -0600

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





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

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