**From:** Daniel, Erik S. (*Daniel.Erik@mayo.edu*)

**Date:** Fri Mar 17 2000 - 06:07:48 PST

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Jim-

*> Can we change C without changing the dielectric constant? Let's say we
*

*> change the thickness between conductor and ground plane. We
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*> haven't changed
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*> L (I don't think)
*

Check again. L changes because now the effective volume available for the

magnetic field changes. Increase C by moving the conductor closer to the

plane, and L is necessarily reduced.

- Erik

==================================================================

Erik Daniel, Ph.D. Mayo Foundation

Voice: (507) 284-1634 Guggenheim 1011B

Fax: (507) 284-9171 200 First Street SW

E-mail: daniel.erik@mayo.edu Rochester, MN 55905

==================================================================

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

*> From: Zabinski, Patrick J. [mailto:zabinski.patrick@mayo.edu]
*

*> Sent: Friday, March 17, 2000 8:32 AM
*

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

*> Subject: RE: [SI-LIST] : A basic question
*

*>
*

*>
*

*> Jim,
*

*>
*

*> Z & Pd are related as you state.
*

*>
*

*> Can C be changed without effecting L? Sure. Simply
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*> change the dielectric. As long as you keep the same
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*> physical geometries and only change the dielectric constant,
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*> C will change with no change in L.
*

*>
*

*> In fact, many of the older EM tools (still some today) relied
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*> on the Z and Pd relationship. Essentially, it's easier
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*> to determine C (F/m) for a line than it is L. So,
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*> after the tool would compute C, it would use the Z and
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*> Pd relationship to determine L
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*>
*

*> L = Er/(Co^2 * C)
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*>
*

*> where
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*> L = H/m
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*> Co = speed of light = 3e8 m/s
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*> C = F/m
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*>
*

*> Pat
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*>
*

*>
*

*>
*

*> Pat
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*>
*

*>
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*> > SI List:
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*> >
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*> > I have a question about the relationship between Z and Pd
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*> > (prop. delay). The
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*> > equations used for these two are :
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*> > Z=(L/C)^(1/2)
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*> > and
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*> > Pd=(LC)^(1/2)
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*> > I guess my question has to do with Pd. How can we equate Pd
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*> > to both the
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*> > above equation and the fact that the speed of light is
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*> > C/((er)1/2)? Which
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*> > says that prop. delay is just a function of the dielectric
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*> > constant (or the
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*> > material that light is propagating through).
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*> > Can I really reduce C, without increasing L, and thus reduce
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*> > the Pd of an
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*> > interconnect? If I can't then the Pd=(LC)^(1/2) has problems.
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*> > If I can then
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*> > how does it align with light's speed being just a function of
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*> > the medium
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*> > it's traveling through?
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*> >
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*> >
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*>
*

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*>
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**Next message:**Daniel, Erik S.: "RE: [SI-LIST] : A basic question"**Previous message:**kholman@celestica.com: "Re: [SI-LIST] : A basic question"**Maybe in reply to:**Peterson, James F (FL51): "[SI-LIST] : A basic question"**Next in thread:**Daniel, Erik S.: "RE: [SI-LIST] : A basic question"

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