How to improve MC pulse distortion in motion controllers through EMC

Pulse signal distortion in motion controllers (MCs) is often caused by reflections, crosstalk, and power supply noise, which can be effectively mitigated through EMC design. To reduce reflections, impedance matching is necessary. This involves connecting a resistor in series at the pulse output to match the transmission line impedance, and connecting a terminating resistor in parallel at the receiving end. Using differential transmission instead of single-ended transmission enhances common-mode noise immunity. Reducing crosstalk requires increasing the spacing between the pulse line and other lines, or inserting a grounding wire.

Power supply noise causes pulse bottom ripples, necessitating an extremely clean power supply for the pulse driver chip, using LC filtering and ample decoupling capacitors. Optimizing PCB layout and shortening pulse loops are also crucial. For long-line transmissions, shielded twisted-pair cable should be used and properly terminated. Measuring the pulse's eye diagram provides a visual assessment of the distortion level and helps pinpoint the cause. Adjusting the matching resistor value, strengthening power supply filtering, or improving grounding can typically significantly improve pulse waveform quality, thereby enhancing system accuracy and stability.