Ambrish,
The interconnect committee voted to make the strong recommendation that
IBIS-ISS subckts used for interconnect do not contain node 0, and
explicitly do not allow node 0 when instantiating IBIS-ISS interconnect
subckts. Reference nodes in these subckts are supplied by component pins
that are Model_type POWER or GND.
The reason it is not a parser error to use Node 0 in interconnect subckts
was that there are many uses of package interconnect models that are not
"power aware". These are traditional Signal Integrity simulations where
the I/O buffer models have static A_puref, A_pdref, A_pcref and A_gcref.
Bottom line is I agree that Node 0 should be removed from the usage in
IBIS buffer models so that they will work with power aware simulations.
Whether it is an error or a warning to use Node 0 in an IBIS-ISS parser is
a valid discussion point.
Walter
-----Original Message-----
From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Ambrish Varma
Sent: Thursday, July 2, 2015 12:48 AM
To: Arpad_Muranyi@xxxxxxxxxx; ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Re: Action required for all IBIS member EDA vendors
Hello Arpad,
Cadence believes nothing in anything IBIS should ever be connected to
global ground.
The word "ground" is confusing and should not be applied anywhere in IBIS,
even if it is qualified with "global" or "local".
Two complicating items for IBIS:
(1) ISS now includes global ground.
(2) The interconnect committee rejected a proposal to eliminate the
application of global ground.
We agree with Scott - the circuit node we are discussing is a "local
reference". Name it anything you wish for a buffer model, but please don't
include the word "ground" in its name or description.
Best regards,
-Ambrish
-----Original Message-----
From: <mailto:ibis-macro-bounce@xxxxxxxxxxxxx>
ibis-macro-bounce@xxxxxxxxxxxxx [ <mailto:ibis-macro-bounce@xxxxxxxxxxxxx>
mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Muranyi, Arpad
Sent: Tuesday, June 30, 2015 11:42 PM
To: <mailto:ibis-macro@xxxxxxxxxxxxx> ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Action required for all IBIS member EDA vendors
This is a request that was made today in the IBIS-ATM meeting to all IBIS
member EDA vendors. We need your reply so we can move forward with the
cleanup process in the IBIS specification regarding "ground".
As you may know, the specification is not very consistent and not always
correct when it comes to the usage of "ground" and its synonyms. We need
to clean this up in the specification because this situation creates
confusion with the already existing power integrity capabilities in the
spec, and the situation will only get even worse with the upcoming new
Interconnect/Package modeling proposal.
The question for which we would like to get a reply from all EDA vendors
is whether we can all agree that C_comp should not be connected to the
ideal ground (or node0) of the simulator, but that is should be connected
to the [Model]s "local ground"
(or pulldown reference).
Please reply to this email with an answer to that question.
Thanks,
Arpad
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