[ibis-macro] Re: redriver in spice simulation

  • From: Ambrish Varma <ambrishv@xxxxxxxxxxx>
  • To: "fangyi_rao@xxxxxxxxxxx" <fangyi_rao@xxxxxxxxxxx>, "ibis-macro@xxxxxxxxxxxxx" <ibis-macro@xxxxxxxxxxxxx>
  • Date: Tue, 12 Mar 2013 16:34:02 -0700

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)


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 

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.


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