[IBIS] RE: C_comp subparameters extraction

One more thing I forgot to mention:

How many power and ground terminals does your buffer have?
If there is more than just one Vcc and one GND terminal,
are you sure you are measuring all the possible paths the
current might take (including the input terminal)?

This might be an "obvious" point, but are you sure that
there are no internal sources in your buffer model
providing power to any part of the buffer?

I hope this helps too...

Thanks,

Arpad
===========================================================

From: owner-ibis@eda.org [mailto:owner-ibis@eda.org] On Behalf Of Muranyi, Arpad
Sent: Monday, March 25, 2013 3:18 PM
To: ibis@eda.org; ibis-users@eda.org
Subject: [IBIS] RE: C_comp subparameters extraction

Rinsha,

Are you making sure that the conditions between your
measurements are the same?

C_comp is a tricky thing.  It can vary with lots of
things.  For example, the C_comp you measure could
be different when the buffer is 3-stated, diving high
or driving low.  It also varies with bias voltage, i.e.
with the voltage at the pad of the buffer.  In order
for the numbers to "add up" you have to make sure that
you add them up when they are under the same conditions.

I hope this helps,

Arpad

From: owner-ibis@eda.org<mailto:owner-ibis@eda.org> [mailto:owner-ibis@eda.org] On Behalf Of Rinsha Reghunath
Sent: Monday, March 25, 2013 5:41 AM
To: ibis@eda.org<mailto:ibis@eda.org>; ibis-users@eda.org<mailto:ibis-users@eda.org>
Subject: [IBIS] C_comp subparameters extraction

Hello,

I was trying out the extraction of C-comp subparameters, namely, C_comp_pullup, C_comp_pulldown, C_comp_power_clamp, and C_comp_gnd_clamp according to the methodology specified in IBIS cookbook version 4.0, section 3.3.1. But the extracted C_comp subparameter values doesnot sum up to the actual C_comp value extracted. How is the Miller cap being taken care of in this case? Is there any documentation on the same?

Thanks & Regards,
Rinsha

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