Experimental investigation on the evolution of a conducted-EMI buck converter after thermal aging tests of the MOSFET

The electrical characteristics of semiconductors and especially the power components are sensitive to temperature variation. Therefore, the thermal behaviour takes an essential place in the design phase. This phase can predict the reliability of semiconductor, its lifetime and the evolution of its performances versus time. Recent studies have been interested in electromagnetic interferences (EMI) variation and in the accelerated aging tests of the power components' effect on their static and dynamic characteristics. This paper presents an experimental investigation of the thermal aging effect of power MOSFETs on the EMI evolution generated by a buck converter circuit. Thermal aging tests are applied on the N-MOS transistors in normal operating conditions in a chopper circuit with a load current of 250 mA. This is in order to promote the thermal effect compared to the electrical one. The impressive thermal aging effect on the amplitude of the conducted EMI, on the switching time, has been discussed.