What impact does the pad design of chip common-mode inductors have on high-frequency performance? ​

The pad design of chip common-mode inductors significantly impacts high-frequency performance, primarily manifesting in parasitic parameters: an excessively large pad can introduce additional parasitic capacitance, leading to a decrease in inductor impedance at high frequencies (such as above 500MHz), thereby weakening the suppression capability of common-mode interference; an excessively small or irregularly shaped pad can increase parasitic inductance, potentially causing resonance peak shifts and leading to filtering failure in specific frequency bands.

Symmetry: asymmetric pads (such as differences in size and shape between the two sides) can cause uneven current distribution in the windings, converting differential-mode interference into common-mode interference and reducing filtering efficiency.

Ground continuity: if the connection between the pad and the ground plane is not continuous (such as insufficient via counts), it can increase ground impedance, resulting in high-frequency interference radiating through the pad.