How should the grounding of the common-mode inductor of a data center switch be designed?

The common-mode inductor in a data center switch does not require additional grounding. Its function is to provide common-mode impedance through differential-mode current cancellation and common-mode current enhancement.

Correct design: The common-mode inductor is connected in series in the signal/power path, with the output connected to the load; ensure symmetrical windings on the PCB layout to avoid imbalance leading to differential-mode to common-mode conversion; avoid copper plating in the surrounding clearance area to maintain unobstructed magnetic fields; high-current inductors such as the CMZ7060A-701T can have a window underneath to enhance heat dissipation.

Incorrect practice: Attempting to ground the common-mode inductor core will disrupt high-frequency characteristics. Actual measurements show a 15dB difference in differential-mode to common-mode gain between correct and incorrect layouts.