[ibis-macro] FW: [IBIS-Users] AMI convolution
- From: "Walter Katz" <wkatz@xxxxxxxxxx>
- To: "IBIS-ATM" <ibis-macro@xxxxxxxxxxxxx>
- Date: Wed, 18 Nov 2009 12:14:15 -0500
All,
In case you are not in ibis-users@xxxxxxx .
Walter
Walter Katz
303.449-2308
Mobile 720.333-1107
wkatz@xxxxxxxxxx
www.sisoft.com
-----Original Message-----
From: Walter Katz [mailto:wkatz@xxxxxxxxxx]
Sent: Wednesday, November 18, 2009 12:00 PM
To: Eric Monteiro; ibis-users@xxxxxxx
Subject: RE: [IBIS-Users] AMI convolution
Eric,
Asking who is responsible for convolution is like asking who is responsible
for Fourier Transform. Convolution is a mathematical technique that EDA
tools can use on the input and output of AMI models, and convolution is a
mathematical technique that can be used inside of the AMI model to apply a
filter. The following describe who may or must use convolution for the
"Preferred Flows". Preferred flows assume both the Tx and Rx model have
Init_Returns_Filter=True and Use_Init_Ouput=True.
Assuming a preferred statistical flow, the EDA tool supplies an impulse
response of the channel to the TX Init function. Inside the Tx Init function
(i.e. inside the AMI model), the model would compute an impulse response of
its filter and return it to the EDA tool. The EDA tool would convolve this
impulse response with the impulse response of the channel and present these
results to the Rx Init. The Rx Init would determine the impulse response of
its filter, and return it to the EDA tool. The EDA tool would then convolve
it with the impulse response that was presented to Rx Init to determine the
impulse response of the channel equalized by both the Tx an Rx filters. The
EDA tool will process this and may use the convolution mathematic technique
(e.g. on probability distribution functions) to generate bathtub curves and
bit error rates. So in the preferred statistical flow the EDA tool does
convolution and the AMI model might not. I could image that the AMI models
may use the convolution technique to generate the impulse response of the
filter.
Assuming the preferred time domain flow, the EDA tool must first run the
statistical flow (it need not analyze the results of Rx Init). The EDA tool
supplies a stimulus waveform to Tx GetWave. The EDA tool may or may not use
the convolution generate this waveform. The Tx GetWave will generate an
equalized stimulus waveform with techniques that may or may not use
convolution. The EDA tool must us uses convolution to apply the impulse
response of the channel with this Tx equalized stimulus waveform. The
waveform is then presented to Rx GetWave. Rx GetWave may or may not used
convolution to apply its equalization filter to it's input. The output of Rx
GetWave is a waveform, and clock ticks. The EDA tool may or may not use
convolution to analyze this waveform to generate bathtub curves and bit
error rate. So in the preferred time domain flow, the EDA tool must use
convolution, and the AMI model might not.
Walter
Walter Katz
303.449-2308
Mobile 720.333-1107
wkatz@xxxxxxxxxx
www.sisoft.com
-----Original Message-----
From: owner-ibis-users@xxxxxxx [mailto:owner-ibis-users@xxxxxxx]On Behalf Of
Eric Monteiro
Sent: Wednesday, November 18, 2009 10:55 AM
To: ibis-users@xxxxxxx
Subject: [IBIS-Users] AMI convolution
Hi everyone,
I was hoping someone could clarify who is responsible for convolution in
IBIS-AMI (EDA tool, or the modeler).
Clearly the convolution involving an FIR filter is upon the modeler, the
convolution I speak of is the one that is done with the channel response.
My understanding has been as follows: (please correct me if I'm wrong)
(a) -- (Tx IC) -- (passive channel) --(b)--(Rx IC)
You force an impulse at (a), measure the response at (b). (b) is the analog
channel response hAC(t). GetWave then needs a wave, which should be an
ideal bit train, convolved with the bit period (creates a piece wise linear
wave) which is then convolved with hAC(t) to produce the wave fed into
GetWave. There was discussion as to whether the modeler or the EDA tool
should do the above convolution. Has it been decided who this task falls
on?
Best Regards,
Eric Monteiro
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