[SI-LIST] Re: Spreading Inductance
- From: steve weir <weirsi@xxxxxxxxxx>
- To: "Hill, John" <John.Hill@xxxxxxxxxx>,<Sirisha.Godavarthy@xxxxxxxxxxxx>, <Tim.J.Nash@xxxxxxxxxxxxx>,"silist" <si-list@xxxxxxxxxxxxx>
- Date: Mon, 25 Sep 2006 08:46:17 -0700
John, it is just English / Metric conversion:
1.257E-6 H/m * 0.0254 m/inch = 31.92 H/inch
Best Regards,
Steve.
At 08:27 AM 9/25/2006, Hill, John wrote:
>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.
>
>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
>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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