Noise Source Impedance Extraction Method of Switched-Mode Power Supply (SMPS) in PC According to the Frequency Range

Impedance is essential information in solving electromagnetic compatibility problems. This paper proposes a method to measure the noise source impedance of a switched-mode power supply (SMPS) in a PC under operating conditions. Unlike previous research, impedance measurements at low frequencies below 1 MHz increase the received signal using the proposed dual current probe (DCP) method. In particular, unlike conventional research, this method can increase accuracy by increasing the number of wire turns without an amplifier or attenuator. Therefore, the proposed noise source impedance extraction method can be used to solve electromagnetic compatibility (EMC) problems such as electromagnetic interference filter design or to analyze the influence of external electromagnetic pulse.