[SI-LIST] Re: IBIS package R,L,C values
- From: "Muranyi, Arpad" <arpad.muranyi@xxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Mon, 20 Sep 2004 11:45:37 -0700
Sorry for the unreadable post, I sent it UTF-8 encoded
in an attempt to avoid those funny characters, but it
didn't seem to succeed. Hopefully this one (US-ASCII)
will.
Arpad
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-----Original Message-----
From: Muranyi, Arpad=20
Sent: Monday, September 20, 2004 11:29 AM
To: si-list@xxxxxxxxxxxxx
Subject: RE: [SI-LIST] Re: IBIS package R,L,C values
I would like to correct a comment below which said that the RLC
values on the [Pin] list will not have priority over the RLC
values listed in [Package]. The best way to do this correction
is to quote the IBIS specification, which says:
|=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=3D=3D=3D=3D=3D=3D
| Keyword: [Package]
| Required: Yes
| Description: Defines a range of values for the default packaging
| resistance, inductance, and capacitance of the component
pins.
| Sub-Params: R_pkg, L_pkg, C_pkg
| Usage Rules: The typical (typ) column must be specified. If data for
the
| other columns are not available, they must be noted with
"NA".
| Other Notes: If RLC parameters are available for individual pins,
they can
| be listed in columns 4-6 under keyword [Pin]. The
values
| listed in the [Pin] description section override the
default
| values defined here. Use the [Package Model] keyword
for more
| complex package descriptions. If defined, the [Package
Model]
| data overrides the values in the [Package] keyword.
| Regardless, the data listed under the [Package] keyword
must
| still contain valid data.
|-----------------------------------------------------------------------
------=20
From this it should be clear that the more detailed data will
override the less detailed data if available. This includes the
RLC in the [Pin] list sections as well as the [Package Model].
The purpose of the [Package] keyword was to provide an overall
description of the entire package. This is why it has typ., min.,
and max. entries. These values can represent the shortest, longest
and average length lead in the package. Note that the [Pin] list
section doesn't have typ., min., max. values, it only allows one
values per pin. This is because the thinking at the time this
was written in the IBIS spec was that the manufacturing variations
of the lead frame are so small that they are negligible, and the
meaning of each individual pin's RLC was to refine the overall
RLC provided in the [Package] keyword.
The [Package Model] keyword was designed to make a more detailed
lumped and/or distributed description of the package available.
Obviously, this is even better than the lumped RLC on the [Pin]
list, so if available it should be used instead.
However, even this syntax has serious limitations for today's
high speed simulations, so we developed a new and much better,
general purpose interconnect specification, the ICM 1.0. This
can be used for connectors, PCB traces, packages, i.e. any
passive interconnect. I hope some day we will even use it for
modeling the on die passive interconnects with this ICM.
Thanks,
Arpad Muranyi
Intel Corporation
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-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of V S
Sent: Friday, September 17, 2004 8:17 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: IBIS package R,L,C values
Mani,
Every chip has two parts the package and silicon. The
silicon occupies a small area, let us say, 200 mils x
200 mils. While the complete package may be 1 inch x 1
inch. There is an interconnect between the silicon and
the package. This package is modeled using package
R,L,C values. The package interconnect can also be
modeled as a distributed element using ebd files. The
silicon itself have parasitics, mostly capacitive
load. Both the Pin R,L,C and the package R,L,C values
are should be taken into account (Most simulators do
it) when simulating.=20
In your case the package will not be taken into
account in case 2. You should see a box outlining the
driver receive when modeling as "ibis device".
The difference in the two case is usually small -
especially if the mismatch between the package
impedance and the board impedance is not significant.
But it will also depend upon the rise time. The
package impedance must be taken into account if you
are working on simulation correlation. Usually the
measurement are done on the motherboard that is
subtantially far from the actual die ( may be as much
as 1"). In such scenario, the signal at the die is
substantially different from the signal at the die
receiver. In such cases, it may be necessary to take
into account teh package R, L, C values.
=20
Some Comments on Harjeet's replies
The PIN R, L, C values have priority over the
package R,L,C values.
- I do not think there is anything like Pin PIN R, L,
C values having priority over the package R,L,C
values. Both are taken into account.=20
PS: These R, L, C value are lumped values. For fast
edge rate these may not provide accurate results.
- It it true that these values are lumped valued. But
they are accurate in most cases. The vendors may
provide the ebd files that have distributed R,L,C
values rather than the lumped values. I beleive that,
if a vendor thinks that lumped R,L,C values are
"sufficiently accurate" for the frequency of concern ,
it is ok.
VS
--- Harjeet Randhawa
<harjeet.randhawa@xxxxxxxxxxxxxxxxx> wrote:
> The IBIS model file should have these parameters
> embedded in it.
> Specctraquest's Model GUI picks this information
> from the DML file
> itself.
>=20
> The PIN R, L, C values have priority over the
> package R,L,C values.
> If PIN R,L,C are not specified then I guess the
> Speectraquest simulator
> will take the Package R,L,C values into account.
>=20
> You can override the Package as well as Pin R, L, C
> values with your
> defined values.
> But again these should be in line with the package
> used.
>=20
> PS: These R, L, C value are lumped values. For fast
> edge rate these may
> not provide accurate results.=3D20
>=20
> Best Regards,
>
/---------------------------------------------------------/
> Harjeet S Randhawa,
> Nevis Networks India Pvt. Ltd,
> B-101, Bhau Patil Marg,
> 34, Aundh Road, Pune - 411 020.
> Tel: +91-20-403-3900, Xtn:290,
> Fax:+91-20-403-3904,
> Cell: 0-9890130611.
>
/--------------------------------------------------------/
>=20
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of sivagurunathan.mani@xxxxxxxxx
> Sent: Friday, September 17, 2004 1:37 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] IBIS package R,L,C values
>=20
> Hi,
>=20
> In IBIS model there is package properties where
> package R,L,C values are
> defined. Again in pin declaration for each pin RLC
> values are specified.
> What is the difference ,In specctraquest If we are
> assigning model as
> IBIS devices, And if we apply pin by pin with
> specified pin model as
> like IBIS I/O , IBIS Input etc. Will there be any
> difference in
> simulation results? Will package properties taken in
> to account ,if do
> as per case 2?
>=20
> Please help in this regard.
>=20
> Sivagurunathan.M
>=20
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>=20
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