Measurement of the Source Impedance of Conducted Emission Using Mode Separable LISN

Conducted Emission of a Switching Power Supply

Abstract

On the reducing procedure of conducted emissions, it is helpful to know the noise source impedance. This paper presents a method to measure noise source complex impedances of common and differential mode separately. We propose a line impedance stabilization, network (LISN) to measure common and differential mode noise separately without changing LISN impedances of each mode. With this LISN, conducted emissions of each mode are measured inserting appropriate impedances at the equipment under test (EUT) terminal of the LISN. Noise source complex impedances of switching power supply are well calculated from measured results.