[ibis-macro] Re: On-die S-parameters?
- From: <radek_biernacki@xxxxxxxxxxx>
- To: <Arpad_Muranyi@xxxxxxxxxx>, <ibis-macro@xxxxxxxxxxxxx>
- Date: Wed, 5 Mar 2014 00:21:20 +0000
Hi David,
Regarding your question #1 and Arpad's reply, I believe configurability in the
context of "some sort of AMI parameter sweep matrix" may go beyond his reply.
For that you may need the approach of BIRD 155.2 on Dependency Resolution that
is not yet in the released spec. It is, however ratified for the next release
of the spec.
With BIRD 155.2 a specific value of an AMI parameter may control the selection
of the parameter values that Arpad discusses in his reply. And, your executable
model will control that selection, whether internally hard-coded, or based on
what you term as a "sweep matrix", even externally defined.
Yet, I agree with Arpad that manually user selected configurability is already
available in the 6.0 spec.
Radek
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx]
On Behalf Of Muranyi, Arpad
Sent: Monday, March 03, 2014 10:22 PM
To: 'ibis-macro@xxxxxxxxxxxxx'
Subject: [ibis-macro] Re: On-die S-parameters?
David,
I think the short answer is that what you are asking for is now all
officially supported by the v6.0 specification. But here are some
details:
#1) Yes, you can just have one [Model], and use the [External Model]
with language "IBIS-ISS". This will let you implement your analog
buffer model using one or more Touchstone files. You can also parameterize
the IBIS-ISS subcircuit so that the name of the Touchstone file is
a string parameter. This way one [Model] and [External Model] inside
it and a single IBIS-ISS subcircuit can have many different S-parameter
models, each of which can describe a certain buffer impedance, etc...
If your signal swing needs to be changed, you can also parameterize
the D_to_A converter (which acts as the stimulus to the IBIS-ISS
subcircuit) using the new "Converter_Parameters" subparameter of
[External Model].
All of these parameter definitions in the .ibs file can also contain
references to parameter files, and if you reference a .ami file you can
also synchronize these parameters with AMI model parameters.
#2) This is now all in the v6.0 IBIS specification, so no proprietary
solutions are needed to achieve all this.
#3) This modeling approach will give you the correct results as long
as the linear S-parameter model with a trapezoidal (ideal) stimulus
is able to adequately describe your buffer's analog behavior. (In other
words if the buffer is pretty much LTI). But that is the fundamental
requirement of this entire AMI modeling approach, so if your buffer
has strong non-LTI features, AMI would not be suitable anyway.
I hope this answers your questions.
Thanks,
Arpad
===========================================================================
From: ibis-macro-bounce@xxxxxxxxxxxxx<mailto:ibis-macro-bounce@xxxxxxxxxxxxx>
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of David Banas
Sent: Monday, March 03, 2014 8:21 PM
To: 'ibis-macro@xxxxxxxxxxxxx'
Subject: [ibis-macro] On-die S-parameters?
Hi Experts,
Can anyone answer this one:
Let's say I have a Tx with variable analog behavior. That is, things like
output drive strength, output impedance, and output slew rate are user
selectable, in the silicon. In that case:
1. Will the on-die S-parameters approach to analog modeling allow me to
reduce the number of [Model]s in my *.IBS file to one, and make ALL model
behavior, both analog and algorithmic, configurable, via some sort of AMI
parameter sweep matrix in the simulator?
2. If so, is this ready to go, today, in the standard, or does it require
a proprietary approach?
3. Also, will modeling this way give true channel characterization, or
will I be forced to "cheat" making up for some amount of channel
characterization inaccuracy in the algorithmic portion of my model?
Thanks!
-db
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