Design and analysis of noise-reduction transformer based on equivalent circuit

The present paper deals with the analysis of noise-reduction transformer that has a filter function for conductive noise transmission. A simple structured prototype transformer utilizing C-cores is prepared. To determine an optimum design for the noise-reduction transformer, noise attenuation of this transformer is discussed based on the equivalent circuit analysis. The analysis gives a quantitative relation between the circuit parameters and the noise attenuation. High performance noise-reduction transformer that has noise attenuation of -80 dB for a power supply unit of digital devices is developed.