All,
I think we can all agree that an Integrated Circuit "Part" consists of
a die inside of a package (lets puts MCM, DIMM aside for now).
I think we can also agree that it is common for a die to be used in
multiple packages, and a package can be used for multiple dies. IBIS
supports the former (a single .ibs file can have multiple
[Components]), but not the later. The pin_name, signal_name,
model_name (A1 DQ1 DQ) discussion during last week's meeting was at
the heart of this matter.
I think we should agree that evolving IBIS so that it treats the die
and package "independently" is the direction we should be going. Die
centric is signal_name, model_name (DQ1 DQ) while package centric is
pin_name, signal_name(A1 DQ1).
We can do this maintaining IBIS backward compatibility and minimal
impact on IC Vendors, EDA Vendors and Users! We do this by making the
following statements about IBIS:
1.[Pin]
a.Contains a list of all of the connects of the [Component] to the "Board"
b.There are three categories of [Pin] model_name
i.NC
ii.POWER and GND
1.Each unique signal_name has
a.one implied die pad name
b.may have a list of named die pad names
iii.Signal (not NC, POWER or GND)
1.Each unique signal_name corresponds to one of:
a.Unique instance of a single ended Input, Output, or I/O Buffer model
b.One side of a differential Input, Output, or I/O Buffer model
c.Unique instance of a Terminator Model
2.[Die Pad]
a.New Optional Keyword
b.Implicit Die Pad pad_names are
i.POWER and GND unique signal_names
ii.Each unique signal_name when [Pin] model_name is not NC, POWER or GND
c.Named Die Pad pad_names are
i.For signal_names on [Pin]s with model_name POWER or GND
3.[Model] supply keywords
a.PuRef <signal_name>
i.Pullup Reference signal_name
b.PdRef <signal_name>
i.Pulldown Reference signal_name
c.PcRef <signal_name>
i.Power Clamp Reference signal_name
d.GcRef <signal_name>
i.GND Clamp Reference signal_name
Package Interconnect Model ports are [Pin] pin_names and [Die Pad]
pad_names.
On-Die Interconnect Model ports are [Die Pad] pad_names, [Model]
signal ports, and [Model] supply ports.
Just as IBIS currently has a method of associating package models with
both specific pins and a default for all pins, the new package and
on-die modeling should have a method of not only assigning ports of
IBIS-ISS subckts to specific [Pin] pin_names, [Die Pad] pad_names,
[Model] signal ports, and [Model] supply ports, there should also be
methods to assign default package and on-die models to [Model]s.
Walter
Walter Katz
wkatz@xxxxxxxxxx <mailto:wkatz@xxxxxxxxxx>
Phone 303.449-2308
Mobile 303.335-6156
