Re: Modeling - Fast Tr

Wai Yeung Yip ([email protected])
Thu, 5 Sep 96 09:08:53 PDT

Regarding Fabrizio's question on high speed interconnect modeling, I agree with
Eric that the best solution is to do a S-parameter characterization over the
frequency range of his application, either via modeling or measurement. One has
to be careful though that the fixturing closely mimics the actual environment
in which the connector will reside. One can then build an equivalent RLC
circuit model based on the physical construction of the connector and run some
optimization software such as that built into MDS or Hspice to compute the
model parameters. The optimization goal would be to produce a circuit model withcorresponding S-parameter set matching that of the connector. This would require
good insight to come up with a circuit model topology which can yield a good

I think the problem with slicing the connector into smaller sections for direct
RLC modeling is that, as Eric pointed out, the coupling between sections would
be ignored. In addition, when it is a true 3D structure, it may not be clear
how to slice it.

My humble opinion,

> From [email protected] Wed Sep 4 14:08:10 1996
> Date: Wed, 4 Sep 1996 12:37:18 -0700
> From: [email protected] (Ray Anderson)
> To: [email protected]
> Subject: Modeling - Fast Tr
> X-Sun-Charset: US-ASCII
> Content-Length: 1529
> I am forwarding this message from Fabrizio Zanella at Teradyne
> ([email protected]). The mail forwarding system choked but I think
> I have it fixed now.
> Ray Anderson
> -----------------------forwarded message starts here------------------------
> REGARDING Modeling - Fast Tr
> Hope everyone has had a good summer.
> I have a generic question regarding creating interconnect models for
> simulation at extremely fast rise times. The scenario is this: signals with
> 150ps rise time are being transmitted through an interconnect, like a right
> angle connector, which is 200ps long. Since the connector is electrically
> long, what is the best alternative for creating an electromagnetic model that
> will yield accurate results at 150ps edge rates? My options are, using BEM or
> FEM analysis:
> 1) Break connector into seven to ten 2D slices, and create lumped element
> model subcircuits
> 2) Break connector into seven to ten 2D slices, and create distributed model
> subcircuits
> 3) Draw a one section 3D model of the connector, and create a lumped element
> subcircuit.
> 4) Draw a one section 3D model of the connector, and create a distributed
> model subcircuit.
> Any feedback or past experiences or mention of other methods would be greatly
> appreciated.
> Thanks and regards,
> Fabrizio Zanella
> Signal Integrity Engineer
> Teradyne
> 44 Simon Street
> Nashua NH 03060
> 603-791-3542
> FAX 603-791-3046
> [email protected]
> ------------------------end of forwarded message----------------------------
> ----- End Included Message -----