Hello Everyone,
I noticed something while reading the BIRD.
The definition makes the following statement:
"The mean value of the steady state high and low voltages of the channel at the
Rx pad."
Notice that this basically says that the DC_Offset is defined as the DC
component of the
waveform at the Rx die pad. This makes sense, because the channel impulse
response
we pass into the AMI simulation (Tx Init) is based on the waveform at the Rx
die pad.
Now, the problem I see is that in the GetWave flow the Rx GetWave function gets
the
output waveform of the Tx GetWave function (convolved with the channel IR). I
don't
see anything in the spec that Tx GetWave has to return a zero DC component
waveform.
In our discussions it was even said that the Tx GetWave is allowed to return a
waveform
with a DC component.
But ask ourselves the question: What does the waveform coming out of the Tx
GetWave
and convolved with the channel IR represent? As far as I can tell, that
waveform is the
equivalent of the Rx die pad waveform.
So I see a conflict here. The DC_Offset parameter defines the Rx die pad
waveform as
a zero DC component waveform, but at the same time we allow the Tx GetWave
function
to produce a waveform WITH a DC component. I think the definition of this
DC_Offset
parameter implies that the Tx GetWave output must have NO DC component, but we
don't say that anywhere.
Or is my thinking flawed somewhere?
Thanks,
Arpad
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