When using common mode inductance in conjunction with differential mode inductance, how should the parameters of the two be matched?

Common mode inductance suppresses common mode interference (symmetric interference between two wires to ground), while differential mode inductance suppresses differential mode interference (asymmetric interference between two wires).

Parameter matching requires complementary frequency coverage: the effective suppression frequency band of common mode inductance (such as 1kHz-100MHz) and the differential mode inductance (such as 50Hz-10MHz) should overlap smoothly to avoid suppression blind spots. Generally, the resonant frequency of differential mode inductance is slightly higher than that of common mode inductance, covering low-frequency differential mode interference (such as power supply ripple).

Impedance matching: the common mode impedance of common mode inductance should be much larger than the common mode impedance of the circuit (such as ≥10 times), and the differential mode impedance of differential mode inductance should be much larger than the differential mode impedance of the circuit to ensure effective attenuation of interference.

Current compatibility: the rated current of differential mode inductance should match the operating current of the circuit (to avoid saturation), and the rated current of common mode inductance should consider the superposition of common mode current and differential mode current, with both requiring a 20%-50% margin.

Core saturation characteristics: differential mode inductance should use a core with high saturation flux density (such as Sendust) to avoid saturation caused by high differential mode current; common mode inductance should use a core with high magnetic permeability (such as ferrite) to prioritize common mode suppression capability.