Subject: question about monotonicity requirements

From: Koller Katja <[email-masked]>
Date: Tue, 28 Nov 2000 17:35:18 +0100

I have a question regarding the monotonicity of the I-V-curves.
The Ibis 3.2 spec says:

Keywords: [Pulldpwn]...
To be monotonic, the I-V table must meet any of the
following 8 criteria:
1- The CURRENT axis either increases or remains constant as
the voltage axis is increased.
...

Does this apply to the [Pullup]- and  [Pulldown]-curves or to the
resulting curve of [POWER Clamp] + [GND Clamp] + [Pullup/down] ?

Thanks,
Katja Koller

---

From: "Dunbar, Tony" <[email-masked]>
Date: Tue, 28 Nov 2000 12:46:17 -0800

Katja,

In my opinion, there isn't a simple either/or answer to that question to
match your either/or question. My answer(s) are:

1) The spec is worded to mean the individual tables. Also, that's how
ibischk operates and reports non-monotonicity violations.

2) From a simulator stand-point, it is the sum of the curves that matters.

Regards,
Tony Dunbar
Mentor/ICX

-----Original Message-----
From: Koller Katja [mailto:[email-masked]]
Sent: Tuesday, November 28, 2000 10:35 AM
To: [email-masked]'
Subject: question about monotonicity requirements

Keywords: [Pulldpwn]...

Thanks,
Katja Koller

---

From: "Ingraham, Andrew" <[email-masked]>
Date: Tue, 28 Nov 2000 16:22:47 -0500

Note that IBIS does not require curves or tables to be monotonic.

The IBIS spec talks about the monotonicity of individual tables, such as the
[Pullup] curve.  What generally matters to most simulators, is the total I/O
current of the device; however, this is more difficult to check.  The I-V
tables might not line up with one another so some interpolation would be
required, which might introduce errors of its own.  Therefore, ibischk tests
only each table alone for non-monotonic data, rather than the total current.

You can expect to get warnings, especially when the tables are derived by
subtracting different I-V curves from one another (small differences of
large numbers).

Regards,
Andy