Subject: RE: [IBIS-Users] LVDS Modeling Question
From: Muranyi, Arpad (arpad.muranyi@intel.com)
Date: Thu Jul 10 2003 - 09:40:08 PDT
Rick,
Do not mess with the [*** Waveform]s. The [Rising Waveform]
should always have a rising edge, and the [Falling Waveform]
should always have a falling edge in it.
The [Diff Pin] keyword will tell the simulator to put a stimulus
of reversed polarity on the second model's input to make that
work in the opposite direction from the non inverted model.
Even if you just had a single ended buffer, you should not
reverse the [*** Waveform] data. If an inverted output is
needed, use the sub-parameter "Polarity" under the [Model]
keyword.
Arpad Muranyi
Intel Corporation
================================================================
-----Original Message-----
From: Rick Kingen [mailto:Rick.Kingen@motorola.com]
Sent: Thursday, July 10, 2003 9:29 AM
To: ibis-users@eda.org
Subject: [IBIS-Users] LVDS Modelling Question
Hello All,
I have generated a model of an LVDS using s2ibis2. I hand edited the V2.1 ibis model to add V3.2 keywords ot model the LVDS buffers. I have tested the buffer using WINIBIS and LINESIM and see good differential signalling when terminated into a 100 ohm resistor. I have a customer that is asking about the [Rising Waveform] and [Falling Waveform] for the negative driver stating that they are inverted. My question is two fold: 1) should the [Rising Waveform] and [Falling Waveform] for the negative driver be inverted from the [Rising Waveform] and [Falling Waveform] for the positive driver. and 2) does the simulator take the information in the [DIFF PIN] section and determine the polarity of the positive and negative waveform such that the [Rising Waveform] and [Falling Waveform] table are not reversed?
Regards,
Rick Kingen
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