| 摘要 |
PROBLEM TO BE SOLVED: To provide a noise filter which has a large noise attenuation quantity only at a specific frequency, in a wide frequency band including a high-frequency range and is inexpensive and small-sized. SOLUTION: This noise filter is constituted by connecting to an Mn-Zn ferrite ring core with high magnetic permeability a common-mode choke coil 1 provided with two coils, an inter line capacitor 2 connected between the winding beginnings and winding endings of the two coils of the common-mode choke coil 1 and capacitors 3 connected between the winding endings of the coils and the ground, the series-connected resonance circuit of a choke coil 5 for resonance and a capacitor 4 for resonance, and the series-connected resonance circuit of a choke coil 7, for resonance and a capacitor 6 for resonance, to ground point.
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