Switching Nodes: Never route any signal trace underneath a switching node in a power regulator, especially the inductor, to avoid high-frequency noise coupling.
Isolation: For high-speed traces, maintain at least 3x the trace width as a clearance from any other signal trace to minimize cross-talk.
Orthogonal Routing: On adjacent layers, route traces orthogonally to reduce capacitive coupling between layers.
Power planes (i.e using shapes for power routing):
These should be directly underneath or adjacent to IC or BGA pins. Couple them with ground planes to filter power noise effectively.
Ground Planes: These are critical for providing a low-impedance return path for currents, particularly for high-frequency signals.
Ground Short Pads for ground isolating: Used for isolating areas with high-switching currents, ensuring they don’t couple noise into sensitive areas of the board.
Note: Generally a ground plane is sufficient due the natural tendency of high speed current path wanting to return to path of least impedance.
Ground Stitching: Use multiple vias to connect ground planes on different layers, forming a low-impedance mesh.
EMI Control: Use via fences around the perimeter of the board to reduce radiated emissions. The rule of thumb is the the via spacing is 20x smaller than the electrical wave lenght of the highest operation frequency.
Finding the Highest Operating Frequency
Mechanical Rigidity: Use copper thieving or ground pour in empty areas to maintain PCB rigidity.
Note: Thieving is used to achieve rigidity for large and thin PCBs.