RE: [IBIS-Users] [Question] about a true differential buffer in a [Component]

Shulong,

I will start with a quote from the IBIS specification from the
[External Model] section:

| The [Diff Pin] keyword is still required within the same
| [Component] definition when [External Model] describes a true
| differential buffer.  The models referenced by each pin listed
| under [Diff Pin] MUST be the same.

This means that you must have two pins on the [Pin] list calling
the SAME model name, and these two pins must be associated as
a differential pair using the [Diff Pin] keyword.

What may be confusing about this is that we have are instantiating
a [Model] in which we have a true differential [External Model]
that has two I/O terminals.  The name of this single [Model]
is mentioned twice on the [Pin] list, but regardless of that, it
is instantiated only once, because it contains a true differential
model having two I/O terminals.  (If the [Model] contained a normal
single ended model, it would be instantiated once for each pin, a
total of two times).

I hope this gave an answer to your question.

Arpad
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-----Original Message-----
From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of slwu
Sent: Wednesday, April 06, 2005 2:31 AM
To: ibis@eda.org; ibis-users@eda.org
Subject: [IBIS-Users] [Question] about a true differential buffer in a [Component]

Hi Experts,

In IBIS4.1 specification, a true differential buffer has two
polarity-inverted ports,
i.e. 'A_signal_pos' and 'A_signal_neg'... and my question is whether we
also need
two pins in [Component] to map these two ports for only one true
differential buffer?

Thanks
Shulong

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