| 摘要 |
PROBLEM TO BE SOLVED: To configure a common mode filter that is able to attenuate common mode noise over a broad band despite a thin film type.SOLUTION: A common mode filter includes a first coil and a second coil formed in a thin film on a dielectric substrate and connected together in terms of electromagnetic field. A common mode signal is attenuated by the first coil, second coil, and resonance by floating capacitance. The dielectric substrate is provided with a layer of magnetic substance, and in a first frequency band in which the magnetic permeability of the magnetic substance is high, a first attenuation pole A1 occurs by the mutual inductance of the first and second coils and the resonance by the floating capacity. The initial magnetic permeability μi of the magnetic substance is selected so that a second attenuation pole A2 occurs by the mutual inductance of the first and second coils and resonance by the floating capacity, in a second frequency band (the relative magnetic permeability of the magnetic substance ≒1) higher than the first frequency band and exceeding the limit of a snake. |
