[SI-LIST] Re: Spreading Inductance

John, this is the permeability of free space.  It is an observed 
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 =3D u0 / 2=F0 * H * (( ln( R2/R1 ) * KPERF ) +
> >ln( R3/R2 ))
> >- u0 =3D 31.9nH/square
> >- H =3D cavity height
> >- R3 =3D radius from die center to bypass cap ring
> >- R2 =3D radius from die center to via field edge
> >- R1 =3D 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.
> >=20
> >
> >-----Original Message-----
> >From: si-list-bounce@xxxxxxxxxxxxx
>[mailto:si-list-bounce@xxxxxxxxxxxxx] =
> >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 =
> >dimensionless
> >(i.e. nH/sq) and not a function of the distance between two points, =
> >rather a
> >function of aspect ratio of the plane - L x W.  So, the size of the =
> >plane
> >isn't what affects spreading inductance, but its shape does.  Are these
>=
> >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
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> >
> >
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