Subject: RE: [IBIS] waveform fixtures for differential models
From: Angulo, John (john_angulo@mentorg.com)
Date: Mon Sep 29 2003 - 14:09:01 PDT
Without discussing specific product features, I believe it is fair to say that most, if not all major IBIS simulators handle arbitrary resistive V-T table loads correctly. Any value of V_fixture consistent with the rest of the model is okay. (Of all the [Rising Waveform]/[Falling Waveform] subparameters, it is non-resistive loading with L_fixture/L_dut or C_fixture/C_dut that makes it more complicated to recover the buffer's slew behavior. The spec therefore discourages the use of reactive loads.)
John Angulo
Hyperlynx Products
Mentor Graphics Corp.
john_angulo@mentor.com
425-869-2320
-----Original Message-----
From: Mike LaBonte [mailto:milabont@cisco.com]
Sent: Monday, September 29, 2003 1:34 PM
To: IBIS
Subject: [IBIS] waveform fixtures for differential models
We have encountered IBIS models with only 1 rising and 1 falling waveform,
each with V_fixture set to 1/2 of power voltage. These are for differential
buffers where the termination voltage is effectively the midpoint, so it
seems to make sense. My question is, will all IBIS simulators simulate this
model correctly? Or are there simulators that absolutely require waveforms
with V_fixture at both power and ground levels?
Mike LaBonte
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