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

  • From: "Todd Westerhoff" <twesterh@xxxxxxxxxx>
  • To: "'Gregory R Edlund'" <gedlund@xxxxxxxxxx>
  • Date: Wed, 12 Dec 2012 13:51:19 -0500 (EST)

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 <http://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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