Electronic packaging of equipment (switches, routers, and computer servers) commonly divides designs into pluggable subsystems that are mounted onto discrete printed circuit boards (PCBs). These subsystems include backplanes and daughtercards, stacking/mezzanine boards, and a configuration commonly known as a midplane. Midplanes are similar to
backplanes, except that the pluggable modules are inserted into both sides of the board (rather than one side). A specific midplane implementation has front and rear cards orientated orthogonally. These orthogonal system architectures have significant advantages in overall channel performance.

This paper discusses optimization of orthogonal architectures and outlines the overall benefits of using an orthogonal system. The system described is, ultimately, a well-controlled link in terms of impedance, skew, and attenuation management, with significant cost advantages over traditional backplane or midplane designs.