[ibis-macro] AMI-init should pass modified IR to getwave....

  • From: Taranjit Kukal <kukal@xxxxxxxxxxx>
  • To: "'IBIS-ATM'" <ibis-macro@xxxxxxxxxxxxx>
  • Date: Thu, 14 Jun 2012 11:34:20 +0530

Hi All,
When I was implementing AMI model, I found a situation where it was important 
that Rx ami_init needed to pass modified-IR to getwave function.
Reason was that Chip-RDL-routing was available as Impulse-Responses.
Removal for "Use_Init_Output" to make Statistical-flow independent of 
Transient-flow,  is going to break the original intent where init and getwave 
were supposed to work in conjunction with each other handling linear and 
non-linear filtering portions respectively (as shown below)


I would go back to Arpad's suggestion (year 2010) for having two 
Impulse-responses coming out of ami_init

-          One that goes to EDA tool for statistical flow

-          One that gets passed to getwave to allow splitting of 
modeling-effort across init and getwave and make things easy for linear filters.

BIRD120 was brought up that deprecates use of "use_init_output" with a view to 
keep statistical and time-domain simulations independent. But as I think more, 
we need to allow both capabilities. It absolutely does not make sense to 
implement simple linear filters within getwave when we can convolute the 
filter-IR with channel-IR. We should take all steps to make modeling easy and 
ensure enough flexibility.

This way, we cover both the scenarios - those who want to leverage init as 
complement to getwave and those who want to keep statistical-flow purely 
independent. Since this does not bring any disadvantage, I strongly feel that 
we all re-consider outputting two modified-IRs out of init function - one for 
statistical-flow and another one to complement getwave filtering.


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