[ibis-macro] AMI Analog Modeling
- From: "Walter Katz" <wkatz@xxxxxxxxxx>
- To: "IBIS-ATM" <ibis-macro@xxxxxxxxxxxxx>
- Date: Fri, 21 Dec 2012 09:37:41 -0500 (EST)
All,
AMI modeling assumes there is an analog channel that can be represented by
an impulse response. AMI simulations assume that there is a zero impedance
voltage source at the Tx end of the analog model and a infinite impedance
Probe at the Rx end of the analog model.
The impulse response of the channel can be generated a number of ways. One
way is to do a time domain step response of the channel, the impulse
response is the derivative of the waveform at the Rx. A second way is to
cascade into a single s4p the Tx buffer analog model represented as an
s4p, the channel (die to die) represented as an s4p and the Rx buffer
analog model represented as an s4p. The two impulse responses should be
identical (within numerical precision/accuracy). There can be other
methods of generation this impulse response.
According to the reference flows, to do a time domain simulation, the
waveform that is input to Rx AMI_GetWave is the waveform generated by Tx
AMI_GetWave convolved with the impulse response of the channel. An
alternative method of generating the waveform at the Rx AMI_GetWave is to
do a time domain simulation using the waveform generated by Tx AMI_GetWave
(mad differential) as input to the cascaded s4p defined above, and probing
the waveform at the Rx end of the cascaded s4p. This method is not
available with the IBIS analog model (either Legacy IV, or External Model)
because of the interpretation of IBIS models in External Model that they
have digital inputs.
One really needs to understand these statements to understand how AMI
analog modeling is fundamentally different than the existing
interpretation that IBIS models have digital inputs.
Walter
Walter Katz
<mailto:wkatz@xxxxxxxxxx> wkatz@xxxxxxxxxx
Phone 303.449-2308
Mobile 303.335-6156
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