RE: [IBIS-Users] RE: [IBIS] C_comp Max < C_comp Min

Sergey,
 
You are making some valid points. Unfortunately this is
the way it is in the IBIS specification, and I was just
giving you the reasons for why it was written that way.
 
However, there is nothing to prevent anyone to request
that this be changed in the specification. Feel free to
write a BIRD if you feel this is something that should
be changed, and if you feel that this change will be
useful for many IBIS model makers and users.
 
Thanks,
 
Arpad
==========================================================

________________________________

From: Nikonchuk Sergey-R6294C [mailto:R6294C@freescale.com]
Sent: Monday, September 27, 2010 10:04 AM
To: Muranyi, Arpad; ibis@server.eda.org; ibis-users@server.eda.org
Subject: RE: [IBIS-Users] RE: [IBIS] C_comp Max < C_comp Min

Arpad,

There are several times such question come up with long discussion
threads ...

Looks like rule have to be re-defined definitely.

Personally I vote for keeping data as they characterized.

The reason behind is:

- As soon as "It was expected that an EDA tool would allow the
user to try out all possible combinations between min/max curves and
C_comp"

It's don' care how actual values are placed in min/max columns

- From Other side, it would simplify significantly CORRELATION
of IBIS data against simulation/measurements. Basically It's NO WAY to
understand from user/verification engineer how C_comp data was
captured/placed in IBIS file except following by EXACTLY SAME
Voltage/Temperature/Process simulation conditions used for rest of IV/VT
data.

Rather than it would create a mess and Error Bump in validation report.

Regards,

Sergey.

From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On
Behalf Of Muranyi, Arpad
Sent: Monday, September 27, 2010 6:35 PM
To: ibis@server.eda.org; ibis-users@server.eda.org
Subject: [IBIS-Users] RE: [IBIS] C_comp Max < C_comp Min

Fabio,

The reason you are getting that message is because the die capacitance

does not have a direct relationship with the fast/slow process corners

and when we wrote the IBIS specification we decided that it was best

to just put the small number into the min place and the big number into

the max place. It was expected that an EDA tool would allow the user

to try out all possible combinations between min/max curves and C_comp.

Arpad

========================================================================

________________________________

From: owner-ibis@eda.org [mailto:owner-ibis@eda.org] On Behalf Of Fabio
BRINA
Sent: Monday, September 27, 2010 7:12 AM
To: ibis@server.eda.org; ibis-users@server.eda.org
Subject: [IBIS] C_comp Max < C_comp Min

Hello Ibis experts,

 I'm working in CMOS tecnology;

 very often in the C_comp extraction I obtain the Min value bigger then
Max value:

 the values come from ac simulations in these conditions:

 C_comp Min value consider: Vcc Min, Process Min, Temp Max

 C_comp Max value consider: Vcc Max, Process Max, Temp Min

 The Ibis Check output is:

WARNING (line 76) -

    Model mod1: C_comp min value is not the smallest value listed

WARNING (line 76) -

    Model mod1: C_comp max value is not the largest value listed

Is that situation acceptable?

or I have to switch the Min Value with Max Value?

... suggestions are welcome !

Thank you,

Fabio

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