Re: [SI-LIST] : Q: HSPICE w-elements' RLCGs - conversioncoefficients

Ron Miller (rmiller@Brocade.COM)
Wed, 07 Apr 1999 14:04:57 -0700

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Heyfitch

Unless the simulated losses are verified by comparison with the
measured s-parameters of real cables and found to be within .5 db across the
band and within about 5 degrees of phase to 13 Ghz I for one will not accept
any model. The bottom line is the congruence with real world and not
mathematical treatise.

HP Mds/ADS meets these criterion and I will stay with the winner.

Ron

"Heyfitch, Vadim" wrote:

>
>
> XFX field solver (from Quad) among other parameters outputs Rs and G
> - frequency dependent resistance and shunt conductance (accounting for the
> skin resistance and the dielectric dipole relaxation losses, respectively).
> These parameters are extracted based on assumption that
> Rskin(freq)~sqrt(freq) and G(freq)~freq. Same assumption is made in HSPICE
> W-elements. However, I believe, that XFX-extracted parameters Rs and G
> should be scaled by the factors sqrt(4*pi) and 2*pi respectively to be used
> in W-elements. These scaling coefficients DO NOT account for necessary unit
> conversion (from mils to meters, etc.). I arrived to these scaling factors
> by comparing the original Telegrapher equations on page 21-80 of
> "Star-Hspice Manual, Release 1998.2" with those in Quad manual. My concern
> there is that these equations in Hspice manual might be given there only as
> an example, and thus are accurate only to some factor.
>
> Would anyone care to comment?
>
> Another issue... XFX provides an optional fudge factor "lambda" that
> effectively accounts for copper plane/trace surface roughness. This fudge
> factor effectively scales the default copper resistivity in the skin layer.
> The default value of "lambda" is 1.
>
> Has anyone of you done any study as to what this Lambda should be? How does
> this value vary (if at all) from one board vendor to another ? Is there any
> particular value for Lambda if one is going to use XFX' data with Hspice
> W-elements?
>
> Thank you all.
>
> Vadim Heyfitch
> Intel, High-end Sever Division
>
> **** To unsubscribe from si-list: send e-mail to majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP. si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list ****

--
Ronald B. Miller  _\\|//_  Signal Integrity Engineer
(408)487-8017    (' 0-0 ') fax(408)487-8017
     ==========0000-(_)0000===========
Brocade Communications Systems, 1901 Guadalupe Parkway, San Jose, CA  95131
rmiller@brocade.com,  rbmiller@sjm.infi.net

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<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> Heyfitch

Unless the simulated losses are verified by comparison with the
measured  s-parameters of real cables and found to be within .5 db across the
band and within about 5 degrees of phase  to 13 Ghz I for one will not accept
any model.  The bottom line is the congruence with real world and not
mathematical treatise.

HP Mds/ADS meets these criterion and I will stay with the winner.

Ron

"Heyfitch, Vadim" wrote:

 

        XFX field solver (from Quad) among other parameters outputs Rs and G
- frequency dependent resistance and shunt conductance (accounting for the
skin resistance and the dielectric dipole relaxation losses, respectively).
These parameters are extracted based on assumption that
Rskin(freq)~sqrt(freq) and G(freq)~freq. Same assumption is made in HSPICE
W-elements. However, I believe, that XFX-extracted parameters Rs and G
should be scaled by the factors sqrt(4*pi) and 2*pi respectively to be used
in W-elements.  These scaling coefficients DO NOT account for necessary unit
conversion (from mils to meters, etc.). I arrived to these scaling factors
by comparing the original Telegrapher equations on page 21-80 of
"Star-Hspice Manual, Release 1998.2" with those in Quad manual. My concern
there is that these equations in Hspice manual might be given there only as
an example, and thus are accurate only to some factor.

Would anyone care to comment?

Another issue... XFX provides an optional fudge factor "lambda" that
effectively accounts for copper plane/trace surface roughness. This fudge
factor effectively scales the default copper resistivity in the skin layer.
The default value of "lambda" is 1.

Has anyone of you done any study as to what this Lambda should be? How does
this value vary (if at all) from one board vendor to another ? Is there any
particular value for Lambda if one is going to use XFX' data with Hspice
W-elements?

Thank you all.

Vadim Heyfitch
Intel, High-end Sever Division

**** To unsubscribe from si-list: send e-mail to majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP.  si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list ****

-- 
Ronald B. Miller  _\\|//_  Signal Integrity Engineer
(408)487-8017    (' 0-0 ') fax(408)487-8017                 
     ==========0000-(_)0000=========== 
Brocade Communications Systems, 1901 Guadalupe Parkway, San Jose, CA  95131
rmiller@brocade.com,  rbmiller@sjm.infi.net
  --------------B82C143636770253B2D5EBAC-- **** To unsubscribe from si-list: send e-mail to majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP. si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list ****