High speed differential trace with reduced radiation in return path

A method of producing a low interference differential trace, the method comprising:

• forming first and second differential traces on a first surface of a printed circuit board;
• forming a first void section in a ground plane layer joined to a second surface of the printed circuit board, the second surface opposite the first surface, wherein the first void section is formed to one side of the first differential trace;
• determining a length of a second void section based on a target radiation frequency;
• forming a second void section having the determined length on the ground plane layer, the second void section being formed to one side of the second differential trace;
• and
• forming a third void section on the ground plane layer, the third void section joining the first and second void sections.

A high speed differential trace structure comprising:

• a first trace;
• a parallel second trace;
• a printed circuit board layer having a top surface and an opposite bottom surface, wherein the first and second traces formed on the top surface;
• a ground plane layer having a top layer in contact with the opposite bottom surface of the printed circuit board;
• a first void section formed in the top layer of the ground plane layer on one side of the first trace;
• a second void section having a determined length formed in the top layer of the ground plane layer on one side of the second trace, wherein the length of the second void section is determined based on a target radiation frequency;
• and
• a third void section on the first surface of the ground plane layer, the third void section joining the first and second void section.