The CISPR 25 electromagnetic compatibility (EMC) standard requires noise measurements up to 108 MHz, far exceeding the conventional 30 MHz limit, which amplifies the adverse effects of parasitic parameters in traditional noise separators. This paper introduces a novel noise separator with an integrated 20 dB attenuator, engineered to minimize parasitic parameter effects. The proposed design ensures stable 20 dB attenuation across the 150 kHz to 108 MHz range, with CM transmission ratio (CMTR) and DM transmission ratio (DMTR) deviations limited to 5 dB at 108 MHz.
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