Hi Mike,
You are right about the second column. If that column is intended as comments
(not syntax) then a full description should be made (e.g., - the "+" terminal
of the the 1st port).
Radek
From: ibis-interconn-bounce@xxxxxxxxxxxxx
[mailto:ibis-interconn-bounce@xxxxxxxxxxxxx] On Behalf Of Mike LaBonte
Sent: Wednesday, March 09, 2016 10:23 AM
To: ibis-interconn@xxxxxxxxxxxxx
Subject: [ibis-interconn] Re: Touchstone File Shortcut Resolution
As always we need to be cautious when telling EDA tools what to do. To Radek's
point 3, my first questions are whether the model maker is required to think
about what should be done with unconnected ports, and if the model maker is
able to determine one solution that will work "correctly" in all scenarios. The
model maker simply built a model assuming everything is connected, right?
If physics determine that the correct treatment of unconnected ports is always
the port reference impedance, then we can just specify that. But if not, maybe
a subparameter to give the correct treatment is in order, as Radek suggests.
Whether or not we can require such a subparameter depends on how badly it's
needed versus how easily the model maker can provide it. If it's absolutely
needed, that trumps the model maker consideration.
On another note: Although the paragraph has "with N ports" to define N as being
the number of ports, the "Terminals and Ports are associated as follows"
listing has a Port column that lists 1 through N, but then it has "reference"
(in a list of ports). Do we need to clarify that reference is not a port?
Mike
From:
ibis-interconn-bounce@xxxxxxxxxxxxx<mailto:ibis-interconn-bounce@xxxxxxxxxxxxx>
[mailto:ibis-interconn-bounce@xxxxxxxxxxxxx] On Behalf Of ;
radek_biernacki@xxxxxxxxxxxx<mailto:radek_biernacki@xxxxxxxxxxxx>
Sent: Wednesday, March 09, 2016 10:51 AM
To: wkatz@xxxxxxxxxx<mailto:wkatz@xxxxxxxxxx>;
ibis-interconn@xxxxxxxxxxxxx<mailto:ibis-interconn@xxxxxxxxxxxxx>
Subject: [ibis-interconn] Re: Touchstone File Shortcut Resolution
Hi All,
I have some comments regarding the highlighted text.
1. Redundant use, or circular definition using "N ports".
2. We do not need to limit the connection of the (N+1)st terminal to POWER
or GND.
3. Please remind me the syntax for an unconnected terminal. But, in any
case, the default should be an open-circuited port. Port reference impedance
would be acceptable upon a special syntactical designation.
4. The reference terminal must not be unconnected.
5. The term "Parallel connection" is incorrectly used.
Additionally, I hope we will not use the term "shortcut".
Radek
From:
ibis-interconn-bounce@xxxxxxxxxxxxx<mailto:ibis-interconn-bounce@xxxxxxxxxxxxx>
[mailto:ibis-interconn-bounce@xxxxxxxxxxxxx] On Behalf Of Walter Katz
Sent: Tuesday, March 08, 2016 3:53 PM
To: 'IBIS-Interconnect'
<ibis-interconn@xxxxxxxxxxxxx<mailto:ibis-interconn@xxxxxxxxxxxxx>>
Subject: [ibis-interconn] Touchstone File Shortcut Resolution
All,
Based on last week's discussion and some private conversations I would like to
propose we accept the wording that is in Draft 19 with a change indicated in
red below:
For an Interconnect Model using File_TS with N ports, N shall match the number
of ports present in the data of the associated Touchstone 1.x file, or the
value associated with the [Number of Ports] field in the associated Touchstone
2 file. The [Number of Terminals] entry in the Interconnect Model shall be an
integer equal to N+1. Terminal rules are described below:
* The EDA tool shall use the pin_name or signal_name specified for the
associated Terminal "N+1" entry as the reference node for each of the N ports.
For an Interconnect Model with N ports, the Terminals and Ports are associated
as follows:
o Terminal Port
o 1 1
o 2 2
o ...
o N N
o N+1 reference
* If a Port is not connected, then it shall be terminated by the EDA
tool with a resistor to the node on Terminal N+1. The value of this resistance
shall be the value associated with the Port Reference Impedance subparameter.
* Terminal N+1 (reference terminal) shall be connected to a Pin with a
model_name of POWER or GND.
While a model make can do anything he wants inside an IBIS-ISS model, there
needs to be some rules on the terminals in shortcut Touchstone files. I have
tried to summarize as best I can what these rules need to be:
1. An S-Parameter can be used as a shortcut if
a. The signal_name on the reference terminal shall not be a signal_name
on any of the port terminals.
b. All of the ports shall reference the same signal_name as the reference
terminal.
2. Multiple shortcut S-Parameter models can be connected in parallel (e.g.
between pins and buffers). As long as no signal_name in the component shall be
on port terminals in two or more of these S-Parameters.
Walter
There are lots of rules that can be written
Walter Katz
wkatz@xxxxxxxxxx<mailto:wkatz@xxxxxxxxxx>
Phone 303.449-2308
Mobile 303.335-6156
