RE: [IBIS-Users] Question about C_comp and [C Comp Corner]

Bob-san,

Thank you very much!
I can understand.

The information under [C Comp Corner] are completely associated with process/voltage/temperature conditions.
The original C_comp information positioned under the [Model] keyword are sorted by magnitude.

best regaeds.
Kazunori Yamada.

From: Bob Ross [mailto:bob@teraspeedlabs.com]
Sent: Friday, March 06, 2015 1:58 AM
To: KAZUNORI YAMADA; ibis-users@eda.org
Subject: RE: [IBIS-Users] Question about C_comp and [C Comp Corner]

Hello Kazunori Yamada,

[C Comp Corner] is a newer keyword in IBIS to provide
C_comp information that overrides any existing C_comp
information directly positioned under the [Model] keyword.

The information under [C Comp Corner] is intended to be
directly correlated with the other [Model] typ/min/max
column information, as would be extracted under the
same process/voltage/temperature conditions.  Because
of this, the EDA tool is expected to use the same C_comp
column information with the [Model] corner information.
For example, the C_comp min column information would be
used only with the [Model] min column information.

Also, [C Comp Corner] example shows that the entries are
not necessarily positioned by magnitude.  For example,
the min column entries are larger than the max column
entries.

With the original C_comp information positioned under the
[Model] keyword, the column entries are positioned by
magnitude (smallest value under the min column, etc.) to
provide the typ and max and min values to be used.
The EDA tool is expected to allow the user to select any or
all of the C_comp corner values to test a range of solutions
that may exist for different pins.  (Also the original reason
for this approach was that the on-die interconnect portion
extracted as part of C_comp might be different for each pin.)

Best Regards,
Bob



From: owner-ibis-users@eda.org<mailto:owner-ibis-users@eda.org> [mailto:owner-ibis-users@eda.org] On Behalf Of KAZUNORI YAMADA
Sent: Wednesday, March 04, 2015 6:18 PM
To: ibis-users@eda.org<mailto:ibis-users@eda.org>
Subject: [IBIS-Users] Question about C_comp and [C Comp Corner]

Hi experts.

I have a question about C_comp and [C Comp Corner].

In the version 5.1 and later,
I can describe the C_comp* by corners under [Model].
[Model]

C_comp 7.0pF 5.0pF 9.0pF

C_comp_pullup 3.0pF 2.5pF 3.5pF | These four can be

C_comp_pulldown 2.0pF 1.5pF 2.5pF | used instead of

C_comp_power_clamp 1.0pF 0.5pF 1.5pF | C_comp
C_comp_gnd_clamp 1.0pF 0.5pF 1.5pF

Moreover I can describe the C_comp* by corners under [C Comp Corner].

[C Comp Corner]

| variable typ min max

C_comp 7.0pF 9.0pF 5.0pF

|

C_comp_pullup 3.0pF 3.5pF 2.5pF | These four can be

C_comp_pulldown 2.0pF 2.5pF 1.5pF | used instead of

C_comp_power_clamp 1.0pF 1.5pF 0.5pF | C_comp

C_comp_gnd_clamp 1.0pF 1.5pF 0.5pF
|

What is different by both of them?
Is the [C Comp Corner] insignificant already?


best regaeds.

Kazunori Yamada.
Renesas System Design Corp.

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