Browse Prior Art Database

Remote Ground Shield

IP.com Disclosure Number: IPCOM000110475D
Original Publication Date: 1992-Nov-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 1 page(s) / 35K

Publishing Venue

IBM

Related People

Siverling, MM: AUTHOR

Abstract

A return to remote power source from a second outer electromagetic interference (EMI) shield is disclosed.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Remote Ground Shield

      A return to remote power source from a second outer
electromagetic interference (EMI) shield is disclosed.

      A noise source (oscillator and noise producing logic fed by A)
is central to a package.  The power, grounds, and signals at two ends
of the package  (P1 and P-1) tend to have the same noise present, but
one is out of phase with the other.  The signal cable B leading from
the noise source circuitry at one extreme end of the package has a
standard return shield - tied to ground to return common mode noise
(S1).  A second shield (S2) physically outside the first shield is
added and electrically connected to ground on the other (far) side of
the noise source.  This attenuates the EMI emission where as attempts
to simply tie the two grounds together may be ineffective because a
low enough impedance can't be achieved in a conductor tying P1 and
P-1 points together.  Shield to be returned to a power or ground
located physically on the other side of the noise source (see the
figure).

      Disclosed anonymously.