[ibis-macro] Re: redriver in spice simulation

  • From: "Todd Westerhoff" <twesterh@xxxxxxxxxx>
  • To: "'Ambrish Varma'" <ambrishv@xxxxxxxxxxx>
  • Date: Wed, 13 Mar 2013 11:48:28 -0400 (EDT)

Ambrish,



If you’re not including the algorithmic part, then the equalization isn’t 
getting modeled.  Why bother?



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: Ambrish Varma [mailto:ambrishv@xxxxxxxxxxx]
Sent: Wednesday, March 13, 2013 11:46 AM
To: Todd Westerhoff
Cc: fangyi rao; ibis-macro@xxxxxxxxxxxxx
Subject: RE: [ibis-macro] Re: redriver in spice simulation



Todd,

We were discussing how a normal time domain (non-AMI) simulation will work 
with a redriver in the middle of a channel. I suggested that shorting the 
redriver Rx pins with the related Tx should work as the simulator will take 
care of the analog waveforms going out from the Rx and in the Tx – but that 
will not work as we describe below.



Thanks,

Ambrish.



From: Todd Westerhoff [mailto:twesterh@xxxxxxxxxx]
Sent: Tuesday, March 12, 2013 9:24 PM
To: Ambrish Varma
Cc: fangyi rao; ibis-macro@xxxxxxxxxxxxx
Subject: Re: [ibis-macro] Re: redriver in spice simulation



Ambrish,



I guess I missed part of this conversation.  What problem are you trying to 
solve?



Todd.

Image removed by sender. Description: 
cid:EAFF2D52-4B63-4A05-9D24-B96BE375B7E0@eau.wi.charter.com

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: "Ambrish Varma" <ambrishv@xxxxxxxxxxx>
To: "fangyi rao" <fangyi_rao@xxxxxxxxxxx>, ibis-macro@xxxxxxxxxxxxx
Sent: Tuesday, March 12, 2013 7:34:02 PM
Subject: [ibis-macro] Re: redriver in spice simulation

Fangyi,

Actually, if we short the Rx and Tx of the redriver, regular spice 
simulations using IBIS models and analog repeaters will have issues with the 
Tx trying to pullup to power and pulldown to ground.



In that case, redriver simulation within the realm of an IBIS cct, solutions 
can be:



1)      No  spice (non AMI) simulation allowed for redrivers (easier)

2)      Series switch like implementation (harder)



Thanks,
Ambrish.



From: fangyi_rao@xxxxxxxxxxx [mailto:fangyi_rao@xxxxxxxxxxx]
Sent: Tuesday, March 12, 2013 4:58 PM
To: Ambrish Varma; ibis-macro@xxxxxxxxxxxxx
Subject: redriver in spice simulation



Hi, Ambrish;



I am not sure if your suggestion of shorting redriver Rx ibis output pin to 
the redriver Tx ibis input pin in spice simulations will work because in 
spice simulations



1.       legacy Tx ibis model is driven by input signal threshold crossing 
events. That’s not how a redriver Tx half is driven by input signal.

2.       legacy Rx ibis model output is a digital signal of 1’s and 0’s 
(hopefully I am correct here). That’s not what redriver Rx half outputs.



Due to the uncertainties in redriver model behavior in non-AMI simulations, 
I prefer to keep my redriver BIRD separate from Walter’s repeater BIRD, at 
least for now.



Regards,

Fangyi

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