Hi Walter,
In yesterday's ATM meeting, Arpad asked a question about EDA tools' use of
some PAM4 "Out" parameters. I believe he was wondering if the spec should
spell out what EDA tools are expected to do with Out parameter values if
they're returned with each GetWave() block.
I think the gist of your response was that the IBIS spec should define what
the model returns, not tell the tools what to do with it.
In section 10.5 (reserved AMI Jitter parameters), there's a Note that might
be relevant to Arpad's question. The entire Note is copied below, but the
last sentence in particular is:
The EDA tool may report the values returned by the AMI_GetWave function to
the user, but these values shall not be used by the EDA tool to modify or
calculate parameter values passed into simulation models in subsequent
function calls or simulations, or to modify or calculate the simulation
results in any way.
Obviously, PAM4 parameters and Jitter parameters are different. But since
they're all reserved parameters that the spec can fully define, perhaps
this language is relevant. The Jitter parameters provide some precedent
for the spec telling the tool what to do (or what not to do) with Out
parameter values. Just wondering if you think that's relevant to Arpad's
PAM4 parameters question?
Thanks,
Curtis
Note:
If the Jitter and Noise parameters are Usage Info, the EDA tool shall
obtain their values from the AMI parameter (.ami) file, optionally through
a user interface if user selections are available or needed.
If these parameters are Usage Out, the EDA tool shall use the values
returned by the AMI_Init function. It is the model maker’s responsibility
to make sure that the AMI_Init function returns the appropriate value in
these parameters to the EDA tool to achieve successful simulations.
The model’s AMI_GetWave function may also return values in these parameters
to the EDA tool, and these values are not required to be the same as the
values previously returned by the AMI_Init function. The EDA tool may
report the values returned by the AMI_GetWave function to the user, but
these values shall not be used by the EDA tool to modify or calculate
parameter values passed into simulation models in subsequent function calls
or simulations, or to modify or calculate the simulation results in any way.
