[SI-LIST] Re: 10-Layer Stack up
- From: Ed Sayre III <esayre3@xxxxxxxx>
- To: stephen.peters@xxxxxxxxx
- Date: Mon, 23 May 2005 16:08:33 -0400
Stephen,
Superconductors are inductive. They have analogous behavior to, but not
the same as, a normal metal. That is, the skin depth is replaced by the
penetration depth, a temperature dependant phenomena. There is a frequency
dependant behavior to Superconductors known as the kinetic
inductance. This is analogous to the internal inductance of a normal
metal, but representative of the kinetic energy of the superconducting
carriers.
What is really interesting, is that at high frequencies (100GHz) some
superconductors are as lossy as normal metals.
Regards
-Ed
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NORTH EAST SYSTEMS ASSOCIATES, INC
-------------------------------------
"High Performance Engineering & Design"
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dr. Edward Sayre 3rd e-mail: esayre3@xxxxxxxx
NESA, Inc. http://www.nesa.com/
235 Littleton Rd, Unit 2 Tel +1.978.392-8787
Westford, MA 01886 USA Fax +1.978.392-8686
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
At 12:12 PM 5/23/2005 -0700, Peters, Stephen wrote:
>Serious question - is a superconductor non-inductive? Just curious...
>
>Regards,
> Stephen Peters
> Intel Corp.
>
>
>-----Original Message-----
>From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
>On Behalf Of Muranyi, Arpad
>Sent: Monday, May 23, 2005 12:04 PM
>To: si-list@xxxxxxxxxxxxx
>Subject: [SI-LIST] Re: 10-Layer Stack up
>
>Couldn't someone finally invent a non-inductive
>conductor?!?!? - Just a joke... :-)
>
>Arpad
>=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D=
>3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D
>=3D3D=3D
>=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D=
>3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D
>
>-----Original Message-----
>From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
>=3D On Behalf Of steve weir
>Sent: Monday, May 23, 2005 11:55 AM
>To: tmcgonigle@xxxxxxxx; sunil_bharadwaz@xxxxxxxxx; =3D
>si-list@xxxxxxxxxxxxx
>Subject: [SI-LIST] Re: 10-Layer Stack up
>
>Thomas, contrary to popular folklore, the main benefit of a thin =3D
>sandwich=3D20 is not more capacitance but lower inductance.
>
>If you have any doubts, consider that with a high Er dielectric you =3D
>could=3D20 achieve equivalent plane cavity capacitance with a much =
>thicker
>=3D dielectric=3D20 but also much higher inductance. I believe that if =
>you
>model that, it =3D will=3D20 become clear to you that Larry Smith's =
>battle
>cry: "It's the inductance =3D
>
>stupid!" is on the mark.
>
>It is low inductance that presents a low impedance to high=3D20
>frequencies. The planes present a lower inductance than the bypass=3D20
>capacitors, but for it to be useful as a shunt on its own through =
>the=3D20
>cavity capacitance, you have to cross the AR created by the cavity with
>=3D the=3D20 discrete bypass capacitors. Because of the problems that
>presents we =3D have=3D20 seen many proposals to try and find better
>damping, whether it be any of =3D
>
>the resistive techniques or high ESR capacitors that Istvan has =3D
>proposed,=3D20 or raising the net ESR of the discrete network using
>Larry's F^N=3D20 technique. Since by and large most people do not use =
>any
>of the =3D techniques=3D20 either Istvan or Larry have proposed to solve
>that problem, they live =3D with=3D20 it for better or for worse. Under
>those conditions, more capacitance =3D can=3D20 be as much of a problem =
>as
>it can be a benefit. But lower inductance =3D helps=3D20 no matter =
>what.
>
>Steve.
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