Hi Arpad,
In short: Keysight agrees (I have already said this many times at the ATM and
Interconnect meetings), but ...
(1) The meaning of the words GND, A_gnd, "ground", and the ground symbol in
some figures starting with 5.1 needs to be clarified (e.g., by removing/fixing
statements like "A_gnd is a universal reference node, similar to SPICE ideal
node 0.", page 93 in 6.0 - actually that's the only place where the global
ground is explicitly referred to).
(2) The concept of the "local ground" (we do not have to say "rail"), or
"circuit reference node" needs to be clearly established, particularly in the
context of the signal ports - A_signal is just one of the terminals. A_gnd (or
whatever name) must be a legitimate node for all interconnect and package
subcircuits (e.g., in Randy's C_comp BIRD).
(3) The term "port" is also, unfortunately, incorrectly used, particularly in
Section "Multi-lingual ...".
(4) Arpad, your question is somewhat incorrectly stated. Yes, C_comp should be
connected to the "local ground", but there is nothing wrong in certain
simulations to connect that "local ground" to the simulator's global ground
(or node "0"). An example of such a correct use is a single buffer simulation
where it is really up to the user, or EDA platform to select one of the circuit
nodes to be the node "0" and connecting the "local ground" to node 0 is just
fine. Your statement "C_comp should not be connected to the ideal ground (or
node0) of the simulator" should rather read that the connection to the global
ground is not mandated.
(5) I disagree with the alternative "(or pulldown reference)". This may work
only if a fixed voltage (or a short circuit) is maintained between the pulldown
reference terminal and the "local ground".
Radek
-----Original Message-----
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx]
On Behalf Of Muranyi, Arpad
Sent: Tuesday, June 30, 2015 8:42 PM
To: 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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