[ibis-macro] Re: redriver in spice simulation

  • From: "Muranyi, Arpad" <Arpad_Muranyi@xxxxxxxxxx>
  • To: "ibis-macro@xxxxxxxxxxxxx" <ibis-macro@xxxxxxxxxxxxx>
  • Date: Thu, 14 Mar 2013 18:14:23 +0000

Fangyi,

Thanks for the correction, and sorry for the misunderstanding
of your proposal on my part.  It makes more sense now, but I
have a few comments/questions:

Regarding “So I tend to agree to Radek’s suggestion, namely ignoring the 
connection between the Rx half and Tx half in SPICE/non-AMI. But that’s beyond 
the scope of my BIRD.”, If that is the case, the BIRD
should state that explicitly, and propose verbiage for the
specification for a statement like that.  But I am not sure
how much of your BIRD text actually goes into the spec.
Could you explain that?

I would suggest to change the words “input *** model” and
“output *** model” to “receiver *** model” and “transmitter
*** model” to eliminate possible confusions along the lines
we just had in this thread.

I have a question about the nature of the waveforms coming out
of the Rx GetWave and going into the Tx GetWave functions.  In
normal AMI simulations the Rx GetWave output is an analog
waveform which we use to build an eye diagram.  The Tx GetWave
input, on the other hand is a +/- 0.5 volt “digital” bit stream.

In your proposal the Rx GetWave output goes into the Tx GetWave.
Are you assuming that if the model is made for a redriver, the
model maker will know that the Rx GetWave output should be (a
+/- 0.5 V digital waveform) or make the Tx GetWave accept true
analog waveforms?

Another question, which was also mentioned yesterday in the ATM
meeting:  If an .ibs file has multiple Rx and Tx AMI models,
how would the simulator know which Rx goes with which Tx model?

Thanks,

Arpad
==================================================================
From: fangyi_rao@xxxxxxxxxxx [mailto:fangyi_rao@xxxxxxxxxxx]
Sent: Thursday, March 14, 2013 12:21 PM
To: Muranyi, Arpad; ibis-macro@xxxxxxxxxxxxx
Subject: RE: [ibis-macro] Re: redriver in spice simulation

Hi, Arpad;

I think some of your confusion arises from the wrong redriver AMI flow on the 
1st page in your drawing. The correct one, as plotted in my BIRD, is

Rx anlg -> Rx GetWave -> Tx GetWave -> Tx anlg

So the redriver simulation is just two back-to-back regular AMI simulations. 
The only thing special about redriver is that Rx GetWave output is the input to 
Tx GetWave.

Regarding your questions,


1)  how are the analog models used in legacy simulations
FR: My BIRD only concerns with AMI usage, and I don’t think it is meaningful to 
run SPICE simulation on redriver model w/o involving its algorithmic parts. So 
I tend to agree to Radek’s suggestion, namely ignoring the connection between 
the Rx half and Tx half in SPICE/non-AMI. But that’s beyond the scope of my 
BIRD.



2)  how are the analog models used in the IBIS-AMI simulations for
   channel characterization
FR: Given the correct flow described in the beginning of this email, it should 
be clear that in channel characterization, analog model is used in the exact 
same way as in a regular AMI simulation.


3)  how are the analog models used in the AMI flow
FR: Given the correct flow described in the beginning of this email, it should 
be clear that in AMI flow, analog model is used in the exact same way as in a 
regular AMI simulation.


4)  what is the nature of the analog models in either of these flows
FR: Given the correct flow described in the beginning of this email, it should 
be clear that in the nature of analog model is exactly the same as it’s in 
regular AMI flows.

Hope this helps.

Regards,
Fangyi

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