Walter,
I was in the process of writing an email to ask if anyone saw any issues with
BIRD189 and simulators supporting the example model I provided. You have
answered my question, since simulators should support Node 0 if they support
IBIS-ISS. If simulators are not supporting Node 0 inside subcircuits, I need
to know so that I can change Node 0 to "REF" and bring it out of the subcircuit
to assign as an A_gnd terminal (which can then be hooked to the simulator
reference node).
I agree with your motion. I have always thought A_gnd was a shortcut to Node
0. Model makers have access to other terminals for referencing if we want to
avoid Node 0 completely.
Thanks,
Randy
From: ibis-interconn-bounce@xxxxxxxxxxxxx
[mailto:ibis-interconn-bounce@xxxxxxxxxxxxx] On Behalf Of Walter Katz
Sent: Wednesday, March 21, 2018 2:01 PM
To: 'IBIS-Interconnect' <ibis-interconn@xxxxxxxxxxxxx>; ibis-macro@xxxxxxxxxxxxx
Subject: [EXT] [ibis-interconn] Putting to Bed A_gnd
All,
This discussion of A_gnd has gotten way out of control, unnecessary and a huge
waste of time.
A_gnd should be defined as a Global Simulator Reference Node (e.g. Node 0).
* If a simulator supports IBIS-ISS then it must support Node 0.
* BIRD 189 is based on IBIS-ISS.
It is very important to note that the model maker who creates BIRD 189 models
can choose to
* Not use A_gnd in his Interconnect model terminals and not use Node 0 in
any of his IBIS-ISS files.
* Use A_gnd in his Interconnect model terminals or use Node 0 in any of his
IBIS-ISS files.
* The currents that go to the component "ground pins" (as defined in the
Component Data Book)" may not account for the currents that go to Node 0.
Almost universally, package interconnect, board interconnect and connector
interconnect SPICE models use Node 0, and almost universally power aware
simulations are "ground base".
I would like to make the following motion:
1. IBIS 189 should state that A_gnd is the Simulator Reference Node (Node 0
in IBIS-ISS)
2. We add the following Note:
* Using A_gnd as Interconnect Model Terminals or Node 0 in IBIS-ISS
subckts may not account for all currents going to "ground" pins, and therefore
potentially introduce simulation results when doing power aware simulations
that are not ground based.
Anyone can write a supporting document on why it is better to make models that
do not use A_gnd or Node 0. This does not belong in the BIRD, but can be
submitted as a supporting document to the BIRD.
Walter
Walter Katz
wkatz@xxxxxxxxxx<mailto:wkatz@xxxxxxxxxx>
978.461-0449 x 133
Mobile 303.335-6156