[ibis-macro] Re: Analog Buffer model - the User's viewpoint
- From: "Muranyi, Arpad" <Arpad_Muranyi@xxxxxxxxxx>
- To: 'IBIS-ATM' <ibis-macro@xxxxxxxxxxxxx>
- Date: Mon, 23 Jan 2012 17:03:08 +0000
Regarding how many corners BIRD 116 supports, I need to
clarify something:
The main thing in BIRD 116 is that it introduces IBIS-ISS
as an official language under the [External Model] and
[External Circuit] keywords. Both of these keywords use
the "Corner" subparameter to define the file and subcircuit
name to be used in the simulation. The "Corner" subparameter
has three (and only three) options, Typ, Min, Max. From
this perspective Walter's statement is correct, BIRD 116
supports three corners only.
However, BIRD 118 adds more to this story. Please recall
that in IBIS v5.0 the [External ***] keywords provide only
a list of the parameter names without any assignment. The
idea behind that was that the EDA tool will collect these
parameter names and provide a dialog for the user with these
names listed in it, and the user make the necessary assignments.
This approach is quite user-unfriendly because the user
has to do extra legwork to figure out the values for all
parameters on their own. For this reason alone, it is
desirable and useful to have the values in the IBIS file
together with these parameters.
The parameter assignment syntax described in BIRD 118 not
only allows a value to be assigned to these parameters, but
also allows an .ami file reference to get the values out of
the .ami parameter file. The multi-valued parameter types
(List, Range, etc...) in the .ami file syntax and the more
elaborate Dependency Table syntax allows each of the above
three IBIS "Corners" to be "extended" to have an unlimited
number of parameter values.
In the case of the S-parameter models, this means that if
we parameterize the file name of the S-element in the
IBIS-ISS subcircuit (yes, string parameters are supported),
the .ami file might contain any number of Touchstone file
names for that S-element and thereby the S-parameter model
can have a practically unlimited number of corners for AMI
modeling purposes.
In summary, while it is true that BIRD 116 and 118 without
an .ami file present allows only three corners, but when
used with .ami files, the number of corners models become
practically limitless (for S-parameter models as well as
any other model types).
Note, however, that it wouldn't take much change in BIRD 118
to extend this parameterization so that even regular IBIS
models (without .ami files) could have unlimited number of
parameter values to extend the corner variations that way
but I am not going to go there until this discussion makes
it necessary.
Thanks,
Arpad
=============================================================
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx]
On Behalf Of Walter Katz
Sent: Friday, January 20, 2012 4:58 PM
To: ambrishv@xxxxxxxxxxx; 'IBIS-ATM'
Subject: [ibis-macro] Re: Analog Buffer model - the User's viewpoint
Ambrish,
BIRD 116 fully support Tstonefile as well, just limited to three corners.
Walter
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