**From:** Jian X. Zheng (*jian@zeland.com*)

**Date:** Fri Mar 02 2001 - 11:24:46 PST

**Next message:**Douglas C. Smith: "[SI-LIST] : Power supply CM output noise"**Previous message:**Matt Bibee: "Re: [SI-LIST] : Total Conductive and dielectric Losses for a microstrip trace"**In reply to:**Matt Bibee: "Re: [SI-LIST] : Total Conductive and dielectric Losses for a microstrip trace"

Hi, Paul:

I use our IE3D full-wave simulator to check your results. It seems to me

your calculated loss is too low.

I assume the conductor is gold with conductivity of 4.9e+7 s/m. For a 75-ohm

line of width 33 mils, the subtrate thickness should be about 33 mils. The

thickness is 0.7 mils. The DK = 3.9.

If I assume there is no dielectric loss, the Alpha = 0.50 dB/m.

If I assume there is no metallic loss, the Alpha = 1.34 dB/m.

If I assume both metallic loss and dielectric loss are there, the Alpha =

1.84 dB/mm.

The calcualted effective DK = 2.86.

I trust the results of our IE3D simulator. Thanks!

Best regards,

-----------------------------------------------------------------------

Jian-X. Zheng, Ph.D

Zeland Software, Inc., 48890 Milmont Drive, 105D, Fremont, CA 94538, U.S.A.

Tel: 510-623-7162, Fax: 510-623-7135, Web: http://www.zeland.com

---------------------------------------------------------------------

*> -----Original Message-----
*

*> From: owner-si-list@silab.eng.sun.com
*

*> [mailto:owner-si-list@silab.eng.sun.com]On Behalf Of Matt Bibee
*

*> Sent: Friday, March 02, 2001 10:36 AM
*

*> To: Denomme, Paul S.
*

*> Cc: si-list@silab.eng.sun.com
*

*> Subject: Re: [SI-LIST] : Total Conductive and dielectric Losses for a
*

*> microstrip trace
*

*>
*

*>
*

*> Your tool should give you the per meter RLGC matrices at your desired
*

*> frequency. The classic equation is:
*

*> alpha=Re{sqrt[(R + jwL)(G +jwC)]} where alpha is in Nepers/m. I
*

*> forget the
*

*> conversion factor. That's the total loss. Is there an advantage
*

*> to seperating
*

*> loss into conductor and dielectric? If you have it available the hspice W
*

*> element can accept RLGC params in matrix format and will model skin and
*

*> dielectric loss.
*

*>
*

*> "Denomme, Paul S." wrote:
*

*>
*

*> > I am currently working on a job and have a microstrip trace on
*

*> > GETEK. The trace width is 33 mils 1/2 oz., running at 1GHz, 75
*

*> ohms, Dk of
*

*> > 3.9, and Loss tangent of .01. I am trying to calculate the
*

*> total conductive
*

*> > loss and the total dielectric losses for this microstrip case. For
*

*> > conductive losses I obtained 0.189dB/M which seems correct to me. I
*

*> > obtained this result from Ansoft 2D analyzer. I am also trying
*

*> to determine
*

*> > the dielectric losses for this trace but I am not sure if I can use a
*

*> > formula for this calculation or not. The formula for
*

*> dielectric loss I have
*

*> > is
*

*> >
*

*> > Ad=(27.3*SQR(Er)*LossTangent)/Wavelength
*

*> >
*

*> > The Ansoft software gave me an effective Dk of 2.88 which is .74 of the
*

*> > Dk=3.9. I am thinking that I could use the .74*Losstangent as
*

*> the effective
*

*> > loss tangent and
*

*> > plug in the effective dielectric constant and the effective loss tangent
*

*> > into the above equation to get the dielectric losses. Can
*

*> anyone tell me if
*

*> > I am way off base on this one? or am I right on the money?
*

*> >
*

*> > I would appreciate any feedback.
*

*> >
*

*> > Regards,
*

*> >
*

*> > Paul S. Denomme
*

*> > paul.denomme@viasystems.com
*

*> >
*

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*>
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*>
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**Next message:**Douglas C. Smith: "[SI-LIST] : Power supply CM output noise"**Previous message:**Matt Bibee: "Re: [SI-LIST] : Total Conductive and dielectric Losses for a microstrip trace"**In reply to:**Matt Bibee: "Re: [SI-LIST] : Total Conductive and dielectric Losses for a microstrip trace"

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