Re: [SI-LIST] : USB modeling

Syed Huq (
Thu, 11 Dec 97 17:03:09 PST


I have done something similar by modeling a SCSI cable on XFX(Crosstalk Field
extractor). I am sure the principle is the same. You practically need to specify
all geometries and material properties within XFX and it will calculate the
odd/even impd, trace velocities and L, C(mutual, self)as well as cross-talk coeffs.

This is where a detailed description of the cable assembly is necessary.
Conductor dia, Insulation thickness, Inner/Outer shield dia as well as
Er of the material is neccesary.

The field-solver(XFX)results were very close to the actual spec BUT the
results also depends on the location of ground.

~ Syed B. Huq ~
~ Signal Management Apps Engineer ~
~ National Semiconductor Corp. ~
~ Tel:(408)721-4874; Fax:(408)721-4785 ~

> Dear all,
> Does anyone know how to model the USB CABLE in quad world (ie, xfx) ?
> I guess someone already made the description in the past to build the
> spec...
> Thanks a lot gentlemen,
> Jean-Christophe PAUTRAT,
> R&D Engineer, Design Engineering
> Corporate Desktop Computer Division,
> H E W L E T T - P A C K A R D.