[ibis-macro] Re: [ibis-interconn] Re: We need to define terms System, Component, Connected, Connection, Module, .ibs Package and Die, .ibs Bare Die

  • From: "Tom Dagostino" <tom@xxxxxxxxxxxxx>
  • To: <wkatz@xxxxxxxxxx>, "'Lynne C. Green'" <lgreen22@xxxxxxxxxxxxxx>
  • Date: Mon, 11 Feb 2013 09:51:03 -0800



There is no reason a package cannot include multiple die.  I see this all
the time in my work.  An IBIS file describes a one to one relationship
between a package pin and a die pad.  The old EBD description added the
ability to have multiple die pads attached to a single package pin. So
memory cards, etc. could be better described in an IBIS file.  But in the
case of multiple die inside the same "package" an IBIS file will work just
fine if a package pin does not go to multiple die pads.


Tom Dagostino


Teraspeed Labs

9999 SW Wilshire St.

Suite 102

Portland, OR 97225



971-279-5325  Office

971-279-5326   FAX

503-430-1065  Cell



www.teraspeed.com <http://www.teraspeed.com/>  


Teraspeed Consulting Group LLC

16 Stormy Brook Road 

Falmouth, ME 04105



From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Walter Katz
Sent: Friday, February 08, 2013 3:35 PM
To: 'Lynne C. Green'
Cc: 'IBIS-Interconnect'; 'IBIS-ATM'
Subject: [ibis-macro] Re: [ibis-interconn] Re: We need to define terms
System, Component, Connected, Connection, Module, .ibs Package and Die, .ibs
Bare Die




I define a package as containing one die, and therefor can be described in a
.ibs file. A Multi-Chip Module contains two or more die (multi means more
than one!), although I think it would be perfectly OK for a EMD containing a
single die. This is a semantically difference, but also has practical usage.
EMD are truly post layout, while .ibs files are often used to describe
pre-layout. .ibs files are often delivered by IP vendors or ASIC vendors to
describe the simulation properties of a buffer or a Tx/Rx buffer pair. It is
also common in a package for the IC Vendor to describe a Typ/Min/Max package
interconnect subckt for all of the Models in a bus, so the difference in
interconnect models for an EMD that represents a package and single die and
a .ibs file is that the EMD is strictly post layout, while the .ibs file can
be either post layout (subckts between the pins and die pads) or pre-layout
where the subckt is defined between the pins and die pads of all the
connections to a [Model]. Crosstalk in an EMD is between actual connections.
Crosstalk in a .ibs model is between actual connections or between and
connection and other connects in the bus, but not necessarily to specific
connections.   This reflects the various ways that IC Vendors are currently
delivering package interconnect models.




From: Lynne C. Green [mailto:lgreen22@xxxxxxxxxxxxxx] 
Sent: Friday, February 08, 2013 5:28 PM
To: Walter Katz
Cc: 'IBIS-Interconnect'; 'IBIS-ATM'
Subject: Re: [ibis-interconn] Re: We need to define terms System, Component,
Connected, Connection, Module, .ibs Package and Die, .ibs Bare Die


Thanks, Walter,

Interesting.  Of course, answers always create new questions...

New nits:
- I love Walter's statement that "connection" could include a DC blocking
cap.  Since that is highly clarifying, perhaps it could be added to the
definition, to emphasize impedance is checked at Nyquist freq? (might need
to spell out Nyquist for the newbie, but that is a different can of worms)
- On second definition of "Connection", plural?
- Newbie question: How is "package" different from "module".   i.e. could a
newbie confuse the two, or perhaps take advantage of features of one that
are not in the other? (not that any IBIS model maker has ever done that
before ;-)
- If there is a difference, is there any "easy" way to make module and
package work the same way (one vs multiple chips, multiple chips in
packages, so they start looking more alike over time).  Am I seeing a
difference of naming, or concept, or syntax, or a real physical difference?


On 2/8/2013 12:43 PM, Walter Katz wrote:



First definition is for "Connected" fixed below. A connection may have a
blocking cap. At DC it is high impedance, but will be low Impedance at
Nyquist. Of course "Low" or "Small" impedance is not very precise. A long
connect with a blocking cap could have in insertion loss of ~30dB at


A bare die is mounted in a Module. The wire bond is in the Module
interconnect and is accounted for in the Module interconnect module, similar
for flip mounted.




From: ibis-interconn-bounce@xxxxxxxxxxxxx
[mailto:ibis-interconn-bounce@xxxxxxxxxxxxx] On Behalf Of Lynne C. Green
Sent: Friday, February 08, 2013 3:21 PM
To: IBIS-Interconnect
Subject: [ibis-interconn] Re: We need to define terms System, Component,
Connected, Connection, Module, .ibs Package and Die, .ibs Bare Die



My usual nits, from a "newbie" viewpoint.

Where will the interconnect between bare die and package be accounted for?
It is not in the IBIS [Model] or the Component [Pin] list.  And apparently
not in "Interconnect Subckt".  Presently accounted for in [Package Model].

Quibbles on zero ohm impedance. 
a) bare die, where wire bond is the package.  Package impedance
approximately 1nH, varies with wire bond length. 
b) bare die, flip mounted (on module or another die).  Package impedance
approximately 0.1nH. 
Neither case is negligible at 100Gb/sec (alpha prototyping now). 

Having two definitions of "Connection" is confusing me.  In simulation, a
"node" means a dead short - one node number, negligible impedance, etc.
While I can see the first definition, the second one is confusing me.

Other than those nits, this is definitely clarifying things for me.


On 2/8/2013 8:00 AM, Walter Katz wrote:



There has been two much confusion on what EMD is and a comprehensive .ibs
package and on-die interconnect solutions, so I propose the following
definitions to clarify future discussions.



A system consists of multiple components that have electrical connections
between them.


A basic building block of a System. A component can be a backplane, PCB,
Connector, Cable, DIMM component, Multi Chip Module, Interposer, package, a
packaged die, a bare die, and other things that have not been invented yet.


Two electrical nodes in a system are connected if the Insertion Loss between
the two points at Nyquist is "Small". 


A connections consists of a list of electrical nodes that are all connected
to each other.


A Module is a Component that has Pins that connect to other system
components, and contains Components and Connections between these
Components, and between these Components and the Module's Pins.


One proposed solution that describes Interconnect Subckts between the Module
Pins and/or Module Components Pins

IBIS Component

Represented by a .ibs file, contains one, and only one die, [Models],
package interconnect between the [Component] [Pins] and Die Pads, on-die
interconnect between the die pads and the [Model].

Bare Die IBIS Component

A special case IBIS Component that represents a physical Die that is mounted
directly in a Module. An example of this is a multi-chip module (MCM) that
contains two are more die that are mounted and wire bonded directly on the
MCM surface. The [Pin] and on-die pad are at the same location, and the
Package model should be treated as a zero ohm resistor.

Interconnect Subckt

An IBIS-ISS subckt or a Touchstone File that has ports that as described
below. The ports may or may not be connected to all of the other ports.



Component Pins

IBIS Package


Die Pads

On-Die Interconnect

Die Pads

[Model] ports


Note that a Module (and therefore EMD) never has connections to [Model]!!!







Walter Katz


Phone 303.449-2308

Mobile 303.335-6156




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