[SI-LIST] Re: true differential IBIS problem
- From: "Muranyi, Arpad" <arpad.muranyi@xxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Mon, 1 Aug 2005 10:47:40 -0700
B.R.
It is quite difficult in general to make an IBIS model=20
which is accurate when you float a bus. The reason is
that very small currents can make a big difference in
the voltage to which it will float. And I am talking
about nA or fA currents here. I would even be cautious
about believing the SPICE models at these low current
levels. For this reason, I would highly recommend=20
that you should use some design techniques which do
not rely on the accuracy of your models at such low
current levels.
Arpad Muranyi
Intel Corporation
--------------------------------------------------------
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
On Behalf Of TerenceHsieh@xxxxxxxxxxxx
Sent: Sunday, July 31, 2005 11:58 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] true differential IBIS problem
Dear All
I have generated a truly differential IBIS .But there are some problem.
When I generate the IBIS's rising/falling waveform, I use 50 ohm
for R_fix and common mode voltage for V_fix. In the sig-xp, if I use
the IBIS to drive a 50 ohm resistor terminated to common mode voltage,
the=20
waveform is exactly right .But I must use the IBIS to drive a
transmission
line without termination. When I use the IBIS to drive a pure
transmission
line the output waveform's DC level will change and common mode voltage
of=20
D+ and D- is different too .How could I generate a truly differential
IBIS=20
for pure transmission line network without termination?
=20
B.R.
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