[SI-LIST] Re: Pre-emphasis and IBIS
- From: "Dagostino, Tom" <tom_dagostino@xxxxxxxxxxx>
- To: "'porsh7@xxxxxxxxx'" <porsh7@xxxxxxxxx>, si-list@xxxxxxxxxxxxx
- Date: Fri, 19 Jul 2002 14:54:49 -0700
If the pre-emphasis is truly data stream or history dependant IBIS at present
cannot handle it. With BIRD 75, adding multi-lingual models, IBIS will be able
to handle this with no problem.
If the pre-emphasis is not data dependent then yes, IBIS can handle it for a
Serdes. We have made IBIS models of pre-emphasis drivers using driver
scheduling to accomplish this.
Tom Dagostino
Modeling Manager
Mentor Graphics Corp.
SAS
tom_dagostino@xxxxxxxxxx
503-685-1613
-----Original Message-----
From: porsh7@xxxxxxxxx [mailto:porsh7@xxxxxxxxx]
Sent: Friday, July 19, 2002 1:32 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Pre-emphasis and IBIS
Hi, All
I get an IBIS related question:
If a SerDes comes with Pre-emphasis feature, can IBIS
model properly represent pre-emphasis characteristics?
Is the following statement true?
---------
Pre-emphasis makes the output characteristic data
dependent. IBIS cannot switch model on the fly depending
on input data.
---------
Is there any new development at IBIS side to adapt the
pre-emphasis?
Or any IBIS driven SI tools can switch on the fly for
pre-emphasis?
A brief of Pre-emphasis
-------------------------
Pre-emphasis means that for data with transition,
there's extra boost on the output amplitude compared to
when there's no data transition. That makes the
characteristic of the SerDes data dependent. This is
used to equalize the lowpass characteristics of PCB
trace and materials, allowing better signal integraty.
e.g. an output for bit pattern "00" and pattern "10",
even though in both cases, the second bit is a "0" but
they will have different amplitudes.
-------------------------
IBIS is a static model meaning for the same input,
always gives the same output. That's why there's no way
IBIS can have different model depending on the data
input. If they don't have pre-emphasis, then there's no
problem.
Would like to hear any feedback on this.
Thanks a lot!!
Porsh
01:30PM 07/19/02
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