High Speed PCB Layout: Physical Design Issues of Highspeed Interfaces

ABSTRACT

Moore’s law, applied to data rates, has pushed PCB circuits so fast that the layout becomes part of the circuit. In designs such as DDR3 and PCIe, the fastest memory and high-speed serial performance comes with very specific physical layout requirements that are not obvious. Unless you are thinking like an RF designer, there are many unexpected challenges to a successful high-speed layout. A point-to-point differential pair doesn’t mean the layout is dirt easy; it means the design challenges have transformed. Keeping in mind that the board is part of the electrical design, we will outline the important high-speed considerations and efficient ways to account for them in high-speed PCB layouts. The approach to board design must start with power and layer planning, include high speed specific rules, and pull in a couple high-speed-specific design disciplines, such as feature automation and signal integrity (SI) simulation.