[SI-LIST] Re: package SSN model accuracy requirements
- From: "Pratt, Gary" <gary_pratt@xxxxxxxxxxx>
- To: <ray.anderson@xxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Wed, 9 Mar 2005 07:33:56 -0500
I should add, that in the case of configurable drivers, the
configuration software could easily write an IBIS 4.1 file which would
reflect the exact programming of the drivers (and even which driver are
switching and which are not). This could save the user a huge amount of
time in manually configuring the simulation.=20
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Pratt, Gary
Sent: Wednesday, March 09, 2005 6:05 AM
To: ray.anderson@xxxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: package SSN model accuracy requirements
Ray,
If one can generate an accurate s-parameter package model for a bank of
I/O traces and the power planes feeding that bank, there should be no
reason a good simulator couldn't use that data to provide an accurate
simulation of the SSO transient. =3D20
However, I understand the dominant SPICE simulator on the market has
significant convergence and simulation speed issues trying to simulate
large s-parameter models. Fortunately, there are alternatives. I have
personally tested one such simulator which can quickly, accurately, and
reliably simulate s-parameter models of well over one hundred ports (and
can reformat huge s-parameter files into an intermediate format which is
much more manageable in size). =3D20
For maximum accuracy, the s-parameter file should be causal, passive,
have data down to DC and up to the point where the frequency response
stabilizes, and sufficient resolution for smooth transitions from point
to point. A good simulator can enforce these rules and extrapolate and
interpolate missing data, but it is much better if the data is correct
from the start. In fact, the more data in the original file, the
smaller the intermediate formatted data might be.
Combining this with an IBIS 4.1 IC file and AMS driver models can
provide an easy-to-use SSO application that can run in a standard SI
development environment. =3D20
Let me know if you would like more information. Or, if you would like
help developing such an application, contact me offline. =3D20
Gary
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Ray Anderson
Sent: Tuesday, March 08, 2005 10:47 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: package SSN model accuracy requirements
Vadim Heyfitch wrote:
>=3D20
>3) As one should expect, package model accuracy comes at the expense of
model complexity. The complex model would take more CPU time to run than
a simpler one. What would be the acceptable trade-off between the
accuracy, the simulation speed, and the size of the package model
(a.k.a. number of IO pins)?=3D20
>What would be the acceptable simulation time (if defined for 100ns
transient run)??
>=3D20
> =3D20
>
A related question:
Besides utilizing either lumped or distributed RLC or transmission line
realizations of a package model to do SSN simulations, I wonder what the
thoughts and experiences of those on the list have been regarding the
use of s-parameter defined n-port models to do these simulations?=3D20
Depending on the simulator you utilize these models have the potential
to accurately predict SSN performance. Is anyone successfuly using these
models in their simulations?
-Ray
--=3D20
Raymond Anderson
Senior Signal Integrity Staff Engineer
Product Technology Dept.
Package Engineering Group
Xilinx Inc.
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