[SI-LIST] Re: HyperLynx vs Hspice
- From: Chris Cheng <chris.cheng@xxxxxxxxxxxx>
- To: "'miersch@xxxxxxxxxxxxxxxxx'" <miersch@xxxxxxxxxxxxxxxxx>,naveenr@xxxxxxxxxxxxxxx
- Date: Thu, 2 Oct 2003 13:40:45 -0700
Its not as bad as you think. No one is trying to (although some =
consultants
or CAD vendors want to talk me into doing) model the entire =
interconnect
structure between silicon as one single model. Things tends to be
partitioned into smaller blocks and most of them are electrically small
enough to invoke the quasi-static assumption. When is the last time you =
have
a pin or via in a PC board measured in cm ? When is the last time you =
have a
transmission line/stackup in PCB x-section measured in cm instead of =
mils ?
Skin effects and dielectric loss can be easily added to these =
quasi-static
models with excellent correlation results with reality. The key is
partitioning the interconnect appropriately so that quasi-static =
analysis
holds within the section while collectively they represent the reality.
There is nothing in SPICE that prohibit you from adding a discontinuity
model or whatever x-talk you are concern in the interconnect models. =
The
skill of the engineer is in question, not the tool itself.
I am more worry about physically send a 210ps edge out of the package =
than
how to model it at this time.
-----Original Message-----
From: Ekkehard Miersch [mailto:miersch@xxxxxxxxxxxxxxxxx]
Sent: Thursday, October 02, 2003 7:37 AM
To: naveenr@xxxxxxxxxxxxxxx
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: HyperLynx vs Hspice
Hi all,
let=92s assume a circuit is switching with 210psec and the signal=20
propagation speed =3D energy propagation speed is 70psec/cm.
The access of the switching device to charges needed for the switching=20
is restricted to a circle (sphere) of 3cm.
Beyond 3cm a thing like (ideal?) ground is not defined anymore (!),=20
which means none of the electrons outside the 3cm circle can reach the=20
switching device during the switching event of 210psec. And the=20
electrons outside the 2cm circle reach the device only after 140psec,=20
which means pretty delayed.
Just looking at this, I have understanding problems with modelling=20
techniques, assuming e.g. Ideal Ground.
At high speed conditions on a PCB, I have problems with ECAD systems,=20
which use TEM ( e.g. 2D solver), with quasi static TEM solutions, with=20
PEEC without retardation, which ignore losses and/or and the frequency=20
dependence of R,L,C, with algorithms, which approximate the Maxwell=20
Equations, with the assumption of ideal ground. Even Spice is such a=20
tool, if non ideal ground assumptions are left out in the applied Spice =
model. I call these tools conventional tools with which it is however=20
possible to handle large complex structure in acceptable computer=20
running times. But these tools ignore also via- via coupling and via=20
=96ground plane structures and just miss with their answers the boat at =
high speed.
Especially when it is claimed that those conventional tools are High=20
Speed PCB analysis tools. But most of the traditional tools on the=20
market do this. Did the guys, who claim the high speed modelling=20
capabilities of conventional tools forget all the nice things they=20
learned at the university ?
Some ways around this dilemma are shown under=20
www.mentor.com/germany/veranstaltungen/hsconf/ in the paper =
=93High-Speed=20
Design Analyse: Vergleich von Messung und Simulation=93.
I am very interested to learn more about the opinion, that Hyperlynx is =
a 3GHz analysis tool or that Hspice can analyze 10GB/sec nets without=20
having the precise information within that Hspice run about all the net =
discontinuities and the interaction of these nets with their power=20
system through the net vias? The 2 examples Hyperlynx and the straight=20
forward used Hspice are only examples representing the other=20
conventional tools using similar techniques.
Ekkehard
Naveen Reddy wrote:
> Hi Everybody:
> I need to perform some high speed simulations (over 3GHz) for my
> backplane and I currently have the Mentor HyperLynx tool. I have run
> into a little problem. HyperLynx needs IBIS models for simulation
> purposes, whereas most of the vendors provide only spice models and =
not
> IBIS. Although HyperLynx can convert Spice models to IBIS, it does =
need
> a Spice simulator to do that.
>=20
> I am a little confused here and am hoping I can have these questions
> answered.
>=20
> 1. Can I use just Hspice to perform all my high speed simulations or =
is
> HyperLynx a better tool for this application?
> 2. Has anyone had experience with converting 3D spice models to IBIS?
> What are the tradeoffs?
> 3. HyperLynx has three levels of licenses - regular, EXT and GHZ. =
Which
> one should I be using?
>=20
> Thanks in advance.
>=20
> -Naveen.
>=20
>=20
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--=20
EFM Consulting
Dr. Ekkehard Miersch
Dresdener Str.6
D-71101 Schoenaich
Germany
Tel. +49 (0)7031-6571-13
Fax/Tel. +49 (0)7031-6571-14
mobile : +49 (0)172 72 444 55
miersch@xxxxxxxxxxxxxxxxx
EFM.Miersch@xxxxxxxxxxx
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