After today's discussion in the IBIS-ATM group, I have revised my original
slides to clarify or correct several points. The new slides are enclosed.
I am also copying the IBIS-ATM mailing list to ensure the participants there
can see the background conversation.
- MM
From: ibis-interconn-bounce@xxxxxxxxxxxxx
[mailto:ibis-interconn-bounce@xxxxxxxxxxxxx] On Behalf Of Mirmak, Michael
Sent: Tuesday, April 10, 2018 11:55 AM
To: 'radek_biernacki@xxxxxxxxxxxx' <radek_biernacki@xxxxxxxxxxxx>;
ibis-interconn@xxxxxxxxxxxxx
Subject: [ibis-interconn] Re: The Mystery Component
Radek,
Thank you! To clarify, my final question should have been broken into two, and
I believe you answered both. To summarize, if the "Bad Circuit" were the
package for a two-terminal device, with Terminals 2 and 4 connected to the
outside world as [Pin]s on a [Component], then the proposal is to add or assume
a fifth terminal, A_gnd, because the Bad Circuit contains an ideal node 0
connection that is not declared as part of the subcircuit definition.
I just have two remaining concerns:
1) You state that the proposal is to "ensure that A_gnd is treated as an
additional node" - is this treatment to be enforced on the model-maker or is it
something that the EDA tool would be expected to implement? In other words,
would we parse interconnect subcircuits for ideal node 0 content, then reject
any that didn't use the additional A_gnd terminal in the subcircuit definition?
Or would we simply expect EDA tools to instantiate any models containing ideal
node 0 as having an additional terminal, A_gnd? The latter may be easy to
state in the specification and may already be done in some cases; the former
may encounter... resistance.
2) Does this extend only to the [Model] level, or does it extend all the
way to [Pin]? In other words, will the presence of ideal node 0 inside any
part of a [Component] drive the creation/assumption of an A_gnd "pin"?
Thanks again!
- MM
From: radek_biernacki@xxxxxxxxxxxx<mailto:radek_biernacki@xxxxxxxxxxxx>
[mailto:radek_biernacki@xxxxxxxxxxxx]
Sent: Monday, April 09, 2018 12:16 PM
To: Mirmak, Michael
<michael.mirmak@xxxxxxxxx<mailto:michael.mirmak@xxxxxxxxx>>;
ibis-interconn@xxxxxxxxxxxxx<mailto:ibis-interconn@xxxxxxxxxxxxx>
Subject: RE: The Mystery Component
Hi Michael,
Thanks, and yes, you have illustrated the situation right.
First, the "Bad" circuit is not necessarily bad. It may be undesired but if it
is defined that way there are consequences of such a definition.
The following are my comments/additions to the questions you raised in the
final slide.
* Yes, for this specific example. In general, however, no. It depends on
where inside of the subcircuit the connection to ground is present.
* The Bad circuit is already legal in IBIS-ISS spec. And, there already
exist models using the connections to the global ground inside of the
subcircuits. Furthermore, it is conceivable (though not really advisable, nor
enforceable) to rework the subcircuit definition to have the fifth terminal
(e.g., 1 2 3 4 5) added, and then instantiated as "Xmystery_component_1 1 2
3 4 A_gnd mystery_component". However, if this is inside of File_ISS, it
does not solve the issue, just brings it to the [Model] level in the circuit
hierarchy.
* No, Terminal 4 is not in any way special to connect it to A_gnd by
definition. The proposal is to ensure that A_gnd is treated as an additional
node to connect the overall buffer to the external world, and specifically as
the reference node in the I/O port. That's really consistent with the legacy
IBIS "ground-based" modeling.
Radek
From:
ibis-interconn-bounce@xxxxxxxxxxxxx<mailto:ibis-interconn-bounce@xxxxxxxxxxxxx>
[mailto:ibis-interconn-bounce@xxxxxxxxxxxxx] On Behalf Of Mirmak, Michael
Sent: Friday, April 6, 2018 3:25 PM
To: IBIS-Interconnect
(ibis-interconn@xxxxxxxxxxxxx<mailto:ibis-interconn@xxxxxxxxxxxxx>)
<ibis-interconn@xxxxxxxxxxxxx<mailto:ibis-interconn@xxxxxxxxxxxxx>>
Subject: [ibis-interconn] The Mystery Component
Per today's IBIS Interconnect discussion, I assembled the enclosed three slides
(plus title slide) to illustrate what I believe Radek's proposal is, and the
situation we are trying to address. Note that neither W-elements nor
Touchstone structures are used.
Some simple questions are raised on the final slide. Comments and questions in
return are welcome.
- MM
Attachment:
mystery-component-v2.pdf
Description: mystery-component-v2.pdf
