How to reduce radiation in the MC clock line of motion controller?

Reducing radiation from the clock line of a motion controller (MC) requires a multi-dimensional approach, addressing the source, path, and shielding. Use a clock generator with spread spectrum capabilities to distribute energy across a wider frequency band. Connect a small resistor or ferrite bead, such as the PBZ series, in series at the clock output to slow the rise time. The clock line must reference a complete ground plane and employ stripline or microstrip line structures to control impedance.

When routing, keep clock lines as short as possible and away from I/O ports and board edges. Ground the clock line by placing ground traces on both sides and using ground vias. Provide sufficient power for decoupling the clock chip. If possible, place the clock circuitry on a middle layer of the PCB, using top and bottom ground planes for shielding. For external clock interfaces, use low-capacitance ESD protection devices. Locate clock radiation hotspots using near-field probes and add targeted local shielding. Finally, perform radiated emission testing to ensure clock harmonics meet relevant standard limits.