[ibis-macro] Re: Package modeling comparison
- From: "Walter Katz" <wkatz@xxxxxxxxxx>
- To: "'James Zhou'" <james.zhou@xxxxxxxxxx>, "'IBIS-ATM'" <ibis-macro@xxxxxxxxxxxxx>
- Date: Tue, 4 Sep 2012 14:44:41 -0400 (EDT)
James,
Comments below.
Walter
From: James Zhou [mailto:james.zhou@xxxxxxxxxx]
Sent: Tuesday, September 04, 2012 2:15 PM
To: wkatz@xxxxxxxxxx; IBIS-ATM
Subject: RE: [ibis-macro] Package modeling comparison
Hi Walter,
Thanks for providing the example files. Here is a list of questions I have
on the example files (there are many of them which may take some time to
resolve).
package.emd
(1) It refers to both pin and pad in "interconnect" section, however
only pins are defined in "Pin" section. Should there also be a section to
define "pads"?
a. <WMK> There are only pins of the EMD module, and instances of
either .emd, .ibs, or .ibsx files. Connections are made between pins of
the EMD file and the pins in the .emd, .ibs, or .ibsx files.
(2) "Pkg", "Tx" and "Rx" are instantiated using two different keywords
of "Package_Model" and "Class". However, their syntax and most of the
contents look exactly the same. What are the differences between them?
a. <WMK> The intent is "Package_Model" is the interconnect model for
that pin. "Class" is to assign a package model to a class of pins. Similar
to [Model_Package_IBIS-ISS] in the incremental .ibs file.
(3) "Reference_Designator_Map" points to bare_die.ibsx file. There are
no explicit mapping on pad names. Is the mapping implicit, requiring both
files using the same pad names?
a. <WMK> Yes
(4) What is the difference between Tx and Tx_Coupled and, Rx and
Rx_coupled? What are the benefits of making such distinctions at model
time?
a. Quite often all of the Rx channels got to the outside row of a
BGA (eliminates vias on the Rx board where the series caps are in 802.3),
and Tx go to inner rows of the BGA.
(5) can you please provide examples of pkg_typ.mod pkg_min.mod
pkg_max.mod. What's the syntax of these mod files?
a. <WMK> I purposely left out the .mod files, this should be
transparent to the changes to the IBIS files, they might look like:
i. .subckt
pkg_typ padP padM pinP pinM Length=.017
ii. W1 padP
padM 0 pinP pinM 0 N=2 RLGCMODEL=rlgc L=Length
iii. .model
mname=rlgc .
iv. .ends
pkg_typ
bare_die_ibsx:
(1) Are sNp files allowed when N not equal 4 or 2?
a. <WMK> The only sNp's that IC Vendors currently are delivering are
s4p for differential SerDes drivers and receivers. The intent here was to
demonstrate what IC Vendors want. I would like to see from IC Vendors what
they require. More complicated on die models will require a section
similar to the interconnect section for the package models.
(2) Are "Buffer+ Buffer- Pad+ Pad-" reserved node names? What to do
when N not equal 4 or 2?
a. <WMK> Yes they are reserved node names. More complex on-die
interconnect will require a section similar to the interconnect section
for the package models with Model_Ports data.
(3) Other than Tstonefile, we assume IBIS-ISS is also allowed, what is
the syntax to hook it up?
a. <WMK> More complex on-die interconnect will require a section
similar to the interconnect section for the package models with
Model_Ports data. The bottom line is Users are now requiring IC Vendors to
deliver on-die interconnect as Touchstone files. IC Vendors do not want to
supply IBIS-ISS because it discloses IP and is harder to do and support
than delivering sNp. Bottom line is do not expect to see any SPICE
circuits for channel on-die interconnect. Things may be different for
on-die power distribution, but again we need to see examples from IC
Vendors.
(4) possible typo in line 80, missing "Pad+": (Tstonefile Ports
Pad- Buffer+ Buffer-)
<WMK> Typo, should be:
(Tstonefile_Ports Pad+ Pad- Buffer+ Buffer-)
legacy.ibs
(1) is it the intention to introduce keywords in comment lines for
future standards (ibis 6.0)?
a. <WMK> No, the comment lines where my way of defining the problem
that Arpad and I were to use to demonstrate the difference in our
methodologies.
James Zhou
From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Walter Katz
Sent: Tuesday, September 04, 2012 8:24 AM
To: IBIS-ATM
Subject: [ibis-macro] Package modeling comparison
All,
Enclosed is a zip file containing a presentation and implementations of
"legacy.ibs" in legacy IBIS format, using legacy IBIS files with parameter
tree sections, splitting the IBIS file into an EMD file (parameter tree
format) and a bare-die legacy file, and finally converting the bare-die
legacy file into an IBISx file.
Mike L,
Can you post this please to the IBIS Reflector.
Walter
Walter Katz
wkatz@xxxxxxxxxx
Phone 303.449-2308
Mobile 303.335-6156
_____
This message and any attached documents contain information from QLogic
Corporation or its wholly-owned subsidiaries that may be confidential. If
you are not the intended recipient, you may not read, copy, distribute, or
use this information. If you have received this transmission in error,
please notify the sender immediately by reply e-mail and then delete this
message.
Other related posts:
