Bob,
Example 14 looks good now.
I am still wondering about Example 13. You use A_gnd to ground signal
terminals,
and rely on an internal node 0 connection as the reference connection. I have
two
problems with this example. First, it "promotes" what we do not recommend, the
use of node 0 inside the subcircuit for referencing. Second, if the subcircuit
has an
internal connection to node 0, one might wonder why the signals were grounded
from the outside... They could have been grounded on the inside too... I know,
this way the same subcircuit can be used for different number of signal paths,
but
still, the thought crossed my mind...
So for these reasons, I would prefer to add one more line to the example, not
necessarily in the last row to illustrate that for ISS it doesn't have to be
the last,
and in the comment say that this is for referencing purposes.
Thanks,
Arpad
================================================================
From: ibis-interconn-bounce@xxxxxxxxxxxxx
[mailto:ibis-interconn-bounce@xxxxxxxxxxxxx] On Behalf Of Bob Ross
Sent: Tuesday, January 16, 2018 11:43 PM
To: ibis-interconn@xxxxxxxxxxxxx
Cc: 'IBIS-ATM' <ibis-macro@xxxxxxxxxxxxx>
Subject: [ibis-interconn] Re: IBIS Interconnect BIRD - A_gnd Example Update
All,
Per discussion, Example 14 is now for File_TS, and the N+1th termina linel
reference is connected to A_gnd.
Bob
From:
ibis-interconn-bounce@xxxxxxxxxxxxx<mailto:ibis-interconn-bounce@xxxxxxxxxxxxx>
[mailto:ibis-interconn-bounce@xxxxxxxxxxxxx] On Behalf Of Bob Ross
Sent: Monday, January 15, 2018 2:09 PM
To: ibis-interconn@xxxxxxxxxxxxx<mailto:ibis-interconn@xxxxxxxxxxxxx>
Cc: 'IBIS-ATM'
Subject: [ibis-interconn] Re: IBIS Interconnect BIRD - A_gnd Examples for
IBIS-ISS
Hi Arpad,
I understand and agree with the interpretations below.
A_gnd is not needed if there already exists an internal node 0 in the
subcircuit.
The A_gnd terminal_type could be used to connect to a vdd or vss or all rail
nodes in a subcircuit terminal line to node 0.
While this might not have been the original goal, A_gnd can be used to short to
"0" any other subcircuit terminal line node (including those associated with
I/O's, as Example 13 shows) for a reduced Interconnect Model.
Bob
From:
ibis-interconn-bounce@xxxxxxxxxxxxx<mailto:ibis-interconn-bounce@xxxxxxxxxxxxx>
[mailto:ibis-interconn-bounce@xxxxxxxxxxxxx] On Behalf Of Muranyi, Arpad
Sent: Monday, January 15, 2018 1:51 PM
To: ibis-interconn@xxxxxxxxxxxxx<mailto:ibis-interconn@xxxxxxxxxxxxx>
Cc: 'IBIS-ATM'
Subject: [ibis-interconn] Re: IBIS Interconnect BIRD - A_gnd Examples for
IBIS-ISS
Bob,
To answer your question in a different way, I checked in the IBIS-ISS spec,
node0 and its synonyms are still interpreted as the global ground:
[cid:image001.png@01D38F2E.47463F50]
On the other hand, IBIS-ISS does not support global parameters:
[cid:image002.png@01D38F2E.47463F50]
So YES to the global node0, bit NO to global parameters...
Arpad
=============================================
From: Muranyi, Arpad
Sent: Monday, January 15, 2018 3:40 PM
To: ibis-interconn@xxxxxxxxxxxxx<mailto:ibis-interconn@xxxxxxxxxxxxx>
Cc: 'IBIS-ATM' <ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>>
Subject: RE: [ibis-interconn] Re: IBIS Interconnect BIRD - A_gnd Examples for
IBIS-ISS
My understanding is that A_gnd is the same thing as node0, GND, GND! and
all of its synonyms. So with that in mind, I don't see why someone would
use A_gnd on a terminal line if that subcircuit terminal is also grounded from
the inside of the subcircuit...
Thanks,
Arpad
=============================================================
From:
ibis-interconn-bounce@xxxxxxxxxxxxx<mailto:ibis-interconn-bounce@xxxxxxxxxxxxx>
[mailto:ibis-interconn-bounce@xxxxxxxxxxxxx] On Behalf Of Bob Ross
Sent: Monday, January 15, 2018 2:22 PM
To: ibis-interconn@xxxxxxxxxxxxx<mailto:ibis-interconn@xxxxxxxxxxxxx>
Cc: 'IBIS-ATM' <ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>>
Subject: [ibis-interconn] Re: IBIS Interconnect BIRD - A_gnd Examples for
IBIS-ISS
Arpad,
You raise some good points.
Do we assume that if a (global) node 0 is used in a .iss, it is automatically
connected to the similar node 0?
(So we do not need Example 14.)
Bob
From:
ibis-interconn-bounce@xxxxxxxxxxxxx<mailto:ibis-interconn-bounce@xxxxxxxxxxxxx>
[mailto:ibis-interconn-bounce@xxxxxxxxxxxxx] On Behalf Of Muranyi, Arpad
Sent: Monday, January 15, 2018 11:22 AM
To: ibis-interconn@xxxxxxxxxxxxx<mailto:ibis-interconn@xxxxxxxxxxxxx>
Cc: IBIS-ATM
Subject: [ibis-interconn] Re: IBIS Interconnect BIRD - A_gnd Examples for
IBIS-ISS
Bob,
Thanks for the examples. I wonder about Example 14. What is the purpose of
having a subcircuit definition terminal connected to node0 on the outside (on
the terminal line) when it is also connected to node0 on the inside of the
subcircuit? By the way, since we can't have a .connect statement inside the
subcircuit, the only way to do that would be by using a 0V DC source or a small
value resistor. But an ideal source will most likely end up with a "Voltage
source,
inductor loop" error message, so the only option is a small valued resistor.
But
why would someone want to do that?
Maybe I don't understand it, but I think we could remove Example 14...
Thanks,
Arpad
================================================================
From:
ibis-interconn-bounce@xxxxxxxxxxxxx<mailto:ibis-interconn-bounce@xxxxxxxxxxxxx>
[mailto:ibis-interconn-bounce@xxxxxxxxxxxxx] On Behalf Of Bob Ross
Sent: Monday, January 15, 2018 1:04 PM
To: ibis-interconn@xxxxxxxxxxxxx<mailto:ibis-interconn@xxxxxxxxxxxxx>
Cc: IBIS-ATM <ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>>
Subject: [ibis-interconn] IBIS Interconnect BIRD - A_gnd Examples for IBIS-ISS
All,
Attached are two examples and related text in BIRD189_draft15_v6.
I want to check if my interpretation is correct on these points that are also
mentioned in BIRD189.
- A_gnd can be used to short I/O nodes to ground at several terminal
lines (Example 13)
- A new node on the .subckt line can be created that shorts to an
internal node 0 (since we do not allow "0" to be a node name (Example 14).
Node 0 is global and does not have to be exposed.
- No example is shown for File_TS since the rule is clear that only
the N+1 terminal line can optionally have A_gnd as a reference
Also, we should use lower case "node 0" in BIRD189.
Bob
--
Bob Ross
Teraspeed Labs
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