| 摘要 |
PURPOSE:To obtain a large attenuation over a wide band by connecting two choke coils in series and arranging the choke coils having a core with a small permeability to a position being noise generating source eliminated by a noise filter. CONSTITUTION:The choke coil using a core having a small permeability in the choke coils is arranged to the side of noise generation source eliminated by a noise filter. The attenuation of the noise filter at a high frequency over the HF band depends on the stray capacitance between the input and output of the noise filter, the attenuation is reduced as the stray capacitance is large and the attenuation depending on the impedance of the coil main body is not obtained. One of factors deciding the stray capacitance between the input and output is a distance between the input and output and the reduction in the attenuation is prevented by parting the distance between the input and output as much as possible. Thus, a high frequency noise is attenuated immediately at the input side by arranging the choke coil using a core having a small permeability playing a role of the attenuation effect to the noise input so as to prevent the high frequency noise from being coupled via the stray capacitance between the input and output.
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