Reduction of radio frequency emissions through terminating geometrically induced transmission lines in computer products

摘要

Radio frequency emissions within a computer system having a printed circuit assembly in proximity of a metal surface are reduced by the placement of one or more lossy components electrically connected to a metal plane within the printed circuit assembly. A connector electrically connects the lossy components to the metal surface. In one embodiment, the lossy components include two resistors at opposite ends of an edge of the printed circuit assembly that is closest to the metal surface. In an alternate embodiment, a single lossy component is a resistor placed in the middle of an edge of the printed circuit assembly that is closest to the metal surface. In the alternate embodiment, a second connector at a first end of the edge of the printed circuit assembly that is closest to the metal surface directly connects the metal plane to the metal surface, and a third connector at a second end of the edge of the printed circuit assembly that is closest to the metal surface directly connects the metal plane to the metal surface. A spring is used to connect the printed circuit assembly to the metal surface. Ends of the spring are inserted into vias within the printed circuit assembly. Traces on the printed circuit assembly electrically connect the vias to the lossy component. Similarly, the vias may be directly connected to a ground or power plane without an intervening lossy component.