Evolution study of the ElectroMagnetic Interference for RF LDMOS in series chopper application after thermal accelerated tests

This paper deals with the (EMI) evolution of conducted interferences in common and differential mode of RF LDMOS (Radio Frequency Lateral Diffused Metal-Oxide-Semiconductor) devices applied to a series chopper. In addition their influences on the electrical parameters are studied after various thermal accelerated ageing tests. The experimental results (spectre and waveform parameters) are presented and discussed. The obtained measurements have highlighted that there is a clear increase in the amplitude of resonances on the interference spectra after ageing. The evolution is not the same for all the parameters and for the different thermal tests. The shift is proportional to temperature. To reach a better understanding of the physical mechanisms of parameter's shift after thermal tests, a numerical model (Silvaco-Atlas) was employed to confirm the degradation phenomena. Actually, the charge trapping in the gate oxide causes a decrease in the Miller capacity value (Crss), thereafter in turn a decrease in the disturbances level.