[ibis-macro] Re: IBIS is very clear about Typ, Slow-Weak, and Fast-Strong in section 9.
- From: "Walter Katz" <wkatz@xxxxxxxxxx>
- To: <Arpad_Muranyi@xxxxxxxxxx>, "'IBIS-ATM'" <ibis-macro@xxxxxxxxxxxxx>
- Date: Mon, 10 Oct 2011 13:07:07 -0400 (EDT)
Arpad,
Sorry my memory failed me again. I was talking about "align implicitly".
You just do not get the point of my e-mail. I am in no way attempting to
solve the problems in IBIS. The whole purpose of AMI Corner was to not
continue the IBIS confusion into AMI. I was simply trying to say that IBIS
has a well-defined method of correlating columns in IV and VT table with
typ, slow-weak and fast-strong process corners. The AMI Corner parameters
are treated in the exact same way as the IV and VT columns.
But I will put my two cents in on the IBIS issue. If we had a new
parameter C_Comp_Corner which has typ, slow-weak, fast-strong values, the
EDA tool still has the possibility to use the numerically minimum value of
these three values for fast-strong simulations and the numerically maximum
value for slow-weak simulations. The EDA tool can also use the numerically
minimum and maximum values of the existing parameter C_Comp. Having
parameters have 5 values will just be confusing as all get-out.
Walter
From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Muranyi, Arpad
Sent: Monday, October 10, 2011 12:50 PM
To: IBIS-ATM
Subject: [ibis-macro] Re: IBIS is very clear about Typ, Slow-Weak, and
Fast-Strong in section 9.
Walter,
Regarding: "This what is meant by "in accordance" with corner chosen
to do the simulations by the EDA tool." and: "So if you want to replace
the "in accordance" sentence with", I wonder what text you are
referring to, because I don't see the words "in accordance"
in the debated section. I suspect you are talking about
this sentence:
"| Note that in the context of Algorithmic Model for type 'Corner', <slow
| value> and <fast value> align implicitly to slow and fast corners, ..."
I just want to be sure we are talking about the same thing...
Now, as to the topic itself, regarding: "Since IBIS only defines Typ,
Slow-Weak, and Fast-Strong,", while you are correct that min/max for
the I-V and V-t tables (including [Ramp]) can be interpreted as
"Slow-weak" and "Fast-strong", such interpretation for other
parameters, most notably C_comp, doesn't exist in the spec. We
are not hung up on the interpretation of the I-V and V-t tables,
we are hung up on the interpretation of the complete model which
includes C_comp. Based on the information in an IBIS model we
simply don't know what value of C_comp should be used with the
min or max I-V and V-t tables.
My proposal of extending the IBIS parameters to five values is
to provide a mechanism for the model maker to define what value
should be used for the fast and slow conditions. These values
may or may not be the same as the min or max values. I would
make them optional, and in the case they are not present, the
assumption would be that min=slow and max=fast. For example,
if someone writes:
| variable typ min max
C_comp 7.0pF 5.0pF 9.0pF
5.0pF should be used for a slow corner simulation and
9.0pF for a fast simulation. But if someone writes:
| variable typ min max slow fast
C_comp 7.0pF 5.0pF 9.0pF 8.9pF 5.1pF
Than a slow corner simulation should use 8.9pF and a
fast corner simulation should use 5.1pF.
This approach would not break old models, but would allow
new models to define the fast/slow corners for the analog
models as well.
This approach could be extended to all IBIS parameters which
are treated independently from the I-V and V-t curves.
Thanks,
Arpad
==============================================================
From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Walter Katz
Sent: Tuesday, October 04, 2011 7:25 PM
To: IBIS-ATM
Subject: [ibis-macro] IBIS is very clear about Typ, Slow-Weak, and
Fast-Strong in section 9.
All,
Section 9 of IBIS clearly defines Typ, Slow-Weak and Fast-Strong
IBIS states:
It is permissible to use slow, weak components or models to derive the
data for the "min" column, and to use fast, strong components or models to
derive the data in the "max" columns under the corresponding voltage and
temperature derating conditions for these columns.
And
The voltage and temperature keywords and optionally the process models
control the conditions that define the "typ", "min", and "max" column
entries for all I-V table keywords [Pulldown], [Pullup], [GND Clamp], and
[POWER Clamp]; all [Ramp] subparameters dV/dt_r and dV/dt_f; and all
waveform table keywords and subparameters [Rising Waveform], [Falling
Waveform], V_fixture, V_fixture_min, and V_fixture_max.
The words "permissible" and "optionally" are generally assumed by model
makers and model users that at least for [Voltage Range], and
[Temperature], IV Curves, VT Curves, and dV/dt all associate the Typ, Min,
and Max columns with Typ, Slow-Weak and Fast-Strong.
An AMI parameter with Format Corner simply states that its value to be
chosen by the EDA tool should correspond to the IBIS corner of the IBIS
analog model when generating the Impulse Response of the channel. This
what is meant by "in accordance" with corner chosen to do the simulations
by the EDA tool.
Since IBIS only defines Typ, Slow-Weak, and Fast-Strong, then the three
Format Corner values correspond to Typ, Slow-Weak, and Fast-Strong.
So if you want to replace the "in accordance" sentence with
The three values of an AMI Corner parameter value shall be chosen to
correspond to the IBIS corner of the IBIS analog model when generating the
Impulse Response of the channel.
Walter
Walter Katz
wkatz@xxxxxxxxxx
Phone 303.449-2308
Mobile 720.333-1107
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