[SI-LIST] Re: Spreading Inductance

Steve,

I was under the impression that the Permeability of free space was 4PI
times 10 to the -7. That is 1.257 X 10 to the -6 henrys per meter.=20

This comes from the square of the speed of light being equal to one over
the permeability time the dielectric constant. The dielectric constant
of free space being equal to 8.85 X 10 to the -12 farads per meter.

Where does the per square come from?

Best regards,

John

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of steve weir
Sent: Monday, September 25, 2006 10:59 AM
To: Hill, John; Sirisha.Godavarthy@xxxxxxxxxxxx;
Tim.J.Nash@xxxxxxxxxxxxx; silist
Subject: [SI-LIST] Re: Spreading Inductance

John, this is the permeability of free space.  It is an observed=20
constant behavior.

Best Regards,


Steve.
At 07:30 AM 9/25/2006, Hill, John wrote:
>Steve,
>
>Where does the 31.9nH/Square come from?
>
>Best regards,
>
>John
>
>
>
>
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>-----Original Message-----
>
>From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]
>On Behalf Of steve weir
>Sent: Tuesday, September 19, 2006 12:28 AM
>To: Sirisha.Godavarthy@xxxxxxxxxxxx; Tim.J.Nash@xxxxxxxxxxxxx; silist
>Subject: [SI-LIST] Re: Spreading Inductance
>
>Tim, those equations come from a presentation I made to the SCVEMC
>January 2005.  You can find the presentation in whole on both the
>X2Y, and Teraspeed web
>sites:  http://www.x2y.com/bypass/method/does_position_matter.pdf,
>and http://www.teraspeed.com/publications.html  Note that they apply
>for specific circumstances of calculating spreading inductance
>between a power ring, and a surrounding bypass capacitor ring.  This
>would also work for a single Vdd / Vss pair.  However for more
>complex pin arrays, you really need to solve the plane.  Tools from
>IBM, KAW, Ansoft, or Sigrity are all capable of that task.
>
>Steve.
>At 05:57 AM 9/18/2006, Sirisha Godavarthy wrote:
> >Hi Tim,
> >I got some info regarding spreading inductance.
> >Hope it helps.
> >
> >Plane spreading inductance:
> >
> >- L of PLANE_CAVITY =3D3D u0 / 2=3DF0 * H * (( ln( R2/R1 ) * KPERF ) =
+
> >ln( R3/R2 ))
> >- u0 =3D3D 31.9nH/square
> >- H =3D3D cavity height
> >- R3 =3D3D radius from die center to bypass cap ring
> >- R2 =3D3D radius from die center to via field edge
> >- R1 =3D3D radius from die center to pkg power / ground attachments.
> >- KPERF scaling factor for perforation in via field
> >* For perforations small compared to wavelength area ratio
> >
> >Thanks&Regards,
> >Sirisha.
> >
> >Thanks&Regards,
> >Sirisha.
> >=3D20
> >
> >-----Original Message-----
> >From: si-list-bounce@xxxxxxxxxxxxx
>[mailto:si-list-bounce@xxxxxxxxxxxxx] =3D
> >On Behalf Of Nash, Tim J (EHCOE)
> >Sent: Friday, September 15, 2006 7:56 PM
> >To: silist
> >Subject: [SI-LIST] Spreading Inductance
> >
> > From what I have gathered, spreading inductance of a plane is =3D
> >dimensionless
> >(i.e. nH/sq) and not a function of the distance between two points, =
=3D
> >rather a
> >function of aspect ratio of the plane - L x W.  So, the size of the =
=3D
> >plane
> >isn't what affects spreading inductance, but its shape does.  Are
these
>=3D
> >true
> >statements?  I want to make sure I understand this correctly.
> >Best Regards,
> >Tim
> >
> >
> >-- Binary/unsupported file stripped by Ecartis --
> >-- Type: application/x-pkcs7-signature
> >-- File: smime.p7s
> >
> >
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