RE: [IBIS-Users] ibischk4

Andy, Katja et al,

There is, in fact, a relationship which should be maintained between
[Ramp] data and I-V curves: the relationship between the dV portion of
the [Ramp] values and the R_load load line intercept with the driver I-V
curves.

Simply put, the R_load of [Ramp] defines a load for use in a load line
analysis of the buffer I-V curves. For example, imagine a standard CMOS
"totem-pole" output-only driver with default [Ramp] R_load of 50 ohms.
Now imagine this R_load load line "drawn" across the I-V curves for the
pullup and pulldown. The voltage intercepts of these load lines with
the I-V curves are the full swing voltages of the outputs when driving
into R_load.

Calculate the 20-80% values of these full swing voltages. These 20-80%
values should match the dV portion of the rising and falling [Ramp]
values. If there is no match, then the DC and transient behaviors of
the buffer don't match and will cause the same problems as an I-V vs.
V-T mismatch would.

You can find additional information on this issue in Section 9, "Notes
on Data Derivation Method," at the end of the IBIS specification.

I hope this helps!

- Michael Mirmak
  Intel Corp.
  Chair, EIA IBIS Open Forum
  http://www.eigroup.org/ibis/
  http://www.ibis-information.org/

-----Original Message-----
From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On
Behalf Of Andrew Ingraham
Sent: Wednesday, November 03, 2004 6:56 AM
To: Koller Katja; ibis-users@eda.org
Subject: Re: [IBIS-Users] ibischk4

> does someone know if the ibischk4 checks if the static and
> dynamic curves fit together, when I have only a ramp for
> dynamic information?

I think I don't understand the question. If you have only Ramp data,
you
have no dynamic (V-T) curves, so there's nothing to check.

Ramp data is essentially independent of I-V characteristics.

Regards,
Andy

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Received on Wed Nov 3 09:47:32 2004