Re: IBIS 3.0 model

Joseph Brcich wrote:
>
> I am in the process of creating an IBIS 3.0 for our K6-2 processor.
>
> When using ibischk3 It Gives me the following errors:
> Pull down has decreasing current.
> Gnd clamp has decreasing current.

First off, these are warnings, not errors.

There are a lot of reasons why an I/V curve might be nonmonotonic,
ranging from numerical artifacts to inconsistent test conditions
to real nonmonotonicity due to feedback. Many processors have weak
bus keepers on their I/O lines to prevent float, and that would do
the trick.

> Can anyone tell me what these mean? What charateristic of the data
> should I look at? Is there a document that describes the error messages?
> Most are self explanatory but this one stumped me.

What I'd do is copy & paste the I/V curves into a spreadsheet and
generate the sum and its differences. That should show the effect
up pretty neatly and let you apply the grey colloidial debugger.

-- 
D. C. Sessions
dc.sessions@vlsi.com