[SI-LIST] : How to measure IBIS model form a Chip?

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From: gedlund@us.ibm.com
Date: Thu Nov 09 2000 - 17:37:48 PST


Dear C.H. Chang,

Creating an IBIS datasheet (model) directly from hardware is a difficult
task for all but the simplest buffer chips. One reason is that it is
usually very difficult to put the outputs in the right state on a chip that
has some complex logic function, e.g. a microprocessor or a memory.
Another reason is that a chip is packaged, but simulators like to see
voltage-time tables to be generated from an UNpackaged part (at least the
simulator I use does.) I prefer to generate the IBIS datasheet using
s2ibis2 from a SPICE model extracted from the actual I/O cell layout with
transistor model parameters that represent the actual semiconductor
processing conditions. Pay close attention to the C_comp numbers; s2ibis2
won't help you with these. Then I like to verify the IBIS-based
simulations against SPICE and verify SPICE against test hardware.

You can measure IV curves using your favorite GPIB-controlled power supply
and digital multimeter (with appropriate accuracy). You don't need a
semiconductor parameter analyzer. It's overkill, and it doesn't pump out
enough current. You'll probably need greater than 100 mA. I like to use a
TDR to measure capacitance. Agilent make some nice boxes that have a
high-speed scope and a TDR in one frame. They're pricey, but a necessary
tool in a high-speed test lab.

Check out the IBIS web site under accuracy. You'll find a manual of
techniques called the "I/O Buffer Accuracy Handbook" and a case study.

http://www.vhdl.org/pub/ibis/accuracy/

Remember, if you extract an IBIS datasheet from one sample component, that
may be the only component for which that model is accurate!

Good luck.

Greg Edlund
Advisory Engineer
Electrical Packaging
IBM Server Technology Development
3605 Hwy. 52 N, Dept. HDC
Rochester, MN 55901
gedlund@us.ibm.com

Date: Thu, 09 Nov 2000 15:43:27 -0800
From: CHCHANG <houmay@itri.org.tw>
Subject: [SI-LIST] : How to measure IBIS model form a Chip?

I want to create IBIS model, could anyone tell me how to measure the I-V
curve of the chip?
Which equipment should I prepare?
How could I find the message about the steps?
Or even,Is it possible?

Thank You a lot!!

C.H.CHANG

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