How to reduce high-frequency impedance when grounding the backplane of a motion controller (MC)

Reducing the high-frequency ground impedance of the motion controller's (MC) backplane is crucial for ensuring signal integrity. The backplane should employ a multi-layer design, with at least one layer being a complete, undivided ground plane. The ground plane should be tightly interconnected with the ground pins of each connector using numerous vias, forming a three-dimensional low-impedance structure. Increase the number of ground pins and distribute them evenly around high-speed signal pins. The backplane ground plane should be connected to the chassis ground via multiple low-inductance paths at the power input.

For high-frequency applications, a ground shielding strip can be designed at the backplane edge, ensuring good contact with the chassis sidewall. Control the characteristic impedance of the control signal lines and ensure their return paths are continuous, avoiding ground plane slots. Embedded capacitors or grounding slots can be designed on the ground plane for specific noise frequencies to suppress resonance. After design, the impedance of the backplane ground plane should be measured using a network analyzer to evaluate its performance in the target frequency band. Backplane transmission eye diagram testing should be used to verify the actual improvement in signal quality from ground optimization.