How should the ground planes of the input and output ends of a common-mode inductor be isolated?

The ground planes of the common mode inductor's input terminal (interference side) and output terminal (clean side) need to be physically isolated through the following methods: Set up an "isolation strip" (a copper-free area with a width typically ≥2mm) in the PCB design to prevent direct connection between the input and output ground planes, thus avoiding the formation of a "ground loop" coupling due to interference through the ground plane.

Single-point connection: The input and output grounds are only connected through Y capacitors (bridged across the isolation strip) or system single-point grounding (such as safety grounding) to prevent interference conduction caused by multiple grounding points.

Layer segmentation: If the PCB is a multilayer board, the input and output ground layers can be designed as independent areas, only indirectly connected through the magnetic core of the common mode inductor or a dedicated grounding point.