Junction Temperature Investigations Based on a General Semi-Analytical Formulation of Forward Voltage of Power Diodes

An original semi-analytical model, based on a general formulation of forward-voltage drop of power diodes, is presented. This model allows taking into account both high and low current injection levels, and it is used to highlight the fundamentals of the thermal calibration of power diodes. This is done for device temperature estimation during power cycling tests and thermal characterization. Theoretical results are satisfactorily compared with experimental ones in a wide range of current injection and temperature levels. A clear analysis of the physical behavior is done in order to evaluate self-heating effects and to understand high-temperature effects. The model is used to evaluate the limits of thermal calibration and to highlight the behaviors at low- and high-current injections in these calibrations.