How to divide the digital ground and analog ground of the motion controller MC

Properly separating digital and analog grounds on the PCB of a motion controller (MC) is crucial for controlling noise coupling. Digital circuit grounds are noisier, while analog circuit grounds are sensitive to noise; therefore, they should be physically separated. The separation gap is typically 0.5mm to 2mm. After separation, the digital and analog grounds should be connected at a single point, usually below the ADC or DAC chip, using a 0-ohm resistor or ferrite bead.

Ferrite beads such as the PBZ series provide isolation at high frequencies with very low DC resistance. The analog section should have its own complete ground plane, used only for analog components and traces. The digital section should also have its own ground plane. All signal lines crossing the separation gap must be filtered or isolated, for example, using differential signals or isolators. During layout, analog components should be concentrated in the analog ground area, and digital components in the digital ground area. Verify the separation effect through ground noise measurements and signal integrity tests to ensure that digital noise does not affect analog accuracy.