Subject: RE: [IBIS-Users] On IBIS Model Generation
From: Mohan, Prabhu (Prabhu.Mohan@actel.com)
Date: Tue Sep 17 2002 - 00:41:35 PDT
Hi Jairam,
You are correct. The buffers characteristics will vary with load.
Since there is no real way to know what load the buffer will be driving
and fast edge rates make traces look like 50ohm transmission lines,
most models use 50ohm pullup and pulldown to derive the VT curves.
At this point I think it is upto the simulator vendor to come up
with the appropriate algorithm to extract buffer characteristics
for other loads.
Hope that was of some help.
Prabhu/~
-----Original Message-----
From: S Jairam [mailto:sjairam@ti.com]
Sent: Monday, September 16, 2002 11:48 PM
To: Mohan, Prabhu
Cc: ibis-users@eda.org
Subject: RE: [IBIS-Users] On IBIS Model Generation
Hi Prabhu,
Thanks for the answer. However the flavour of the question still
remains the same. The buffer drive will depend on the load (might not
just be the package load) that will be hooked up. Should not this
again be varied for generating the IBIS model ?
Thanks and Regards,
Jairam.
Mohan, Prabhu writes:
#Hi Jairam,
#
#The package parameters (RLC) are NOT taken into account while generating
the
#IBIS model. They are to be provided seperately to facilitate simulation
#using other (SI) tools.
#
#Ragards
#Prabhu/~
#
#-----Original Message-----
#From: S Jairam [mailto:sjairam@ti.com]
#Sent: Monday, September 16, 2002 10:07 PM
#To: ibis-users@eda.org
#Subject: [IBIS-Users] On IBIS Model Generation
#
#
#
#Hi,
#
# This might sound very dumb a question, but I dont have an
#answer to this.
#
# When IBIS model generation for an IO buffer is in progress,
#only one package load (a set of RLC parameters) is used to calculate
#all the IV curves. Is that valid ? Because in such a case the
#I-V curves of buffer would then be dependent of the package load.
#
# Shouldn't it be that the calculation be done for various load
#points with each load-point providing a set of I-V curves.
#
#Please correct me if I am wrong.
#
#Thanks and Regards,
#Jairam.
#--
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