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PCB structure to enable magnetic switching between traces

IP.com Disclosure Number: IPCOM000196789D
Publication Date: 2010-Jun-15
Document File: 3 page(s) / 235K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method and apparatus to modulate coupling or crosstalk noise between signals in a PCB without cuts or changes to affected trace.

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PCB structure to enable magnetic switching between traces

A PCB trace with surface current will have electromagnetic fields emanating from the current flow and charge distribution. Even though magnetic fields can not be blocked or stopped, metals like iron with high permeability can absorb and redirect magnetic flux. Figure 2 shows how a uniform and local magnetic field can be concentrated through a section of printed circuit board with a magnetic circuit where the north pole is separated from the south pole with a small air gap. A solenoid wrap around an iron core could be a source of an external magnetic field. The magnetic field that is concentrated inside the iron core can skew the surface charge distribution in a pair of traces that form a current loop path. Magnetic field that cuts through the conductors can result in a force on mobile carriers. The force can deflect the mobile carriers in a direction normal to the plane that contains a magnetic field perpendicular to the direction of the current flow. Based on the direction of the magnetic flux, the charged mobile carriers can be deflected or swept to a surface of a rectangular shaped aggressor trace that is far from an adjacent trace or to the surface close to an adjacent trace. An adjacent quiet trace would be the victim trace located close to but outside the external magnetic field.

As shown in figure 1, most of the field strength emanating from surface current and its respective surface charge distribution in a PCB trace without external field applied is concentrated between bottom of signal trace and top of ground shield layer. Wit...