EMI Reduction Technique of Switching Regulators and Its Measurement Verification

This paper presents Electro-Magnetic Interference (EMI) reduction and measurement techniques of DC-DC converters (switching regulators). We have already proposed a simple, inexpensive technique for intentionally broadening and flattening the spectrum of a switching regulator to reduce EMI. This noise spectrum broadening technique involves intentionally introducing pseudo-random dithering of control clock timing, which can be achieved by adding simple digital circuitry. In this paper we will report the measured results of switching regulators that this technique can significantly reduce EMI to the DC-DC converter input voltage source, with regards to peak detection, quasi-peak detection and average detection. The measurements were performed using a standard EMI measurement system in an electro-magnetic shield room (anechoic chamber). キーワード : スイッチング電源, スイッチングノイズ, EMI, EMC, スペクトラム拡散クロック