Today, the main tool used by specialists in power electronics is the digital oscilloscope. As long as it is used to verify correctness of circuits working, its initial accuracy, generally, meets the needs. However, when fast power electronic switch characterization is at sake, required accuracy can't be directly reached. Operating modes must be optimized and corrections must be brought to measurement. Implementation of thèse corrections requires computer help and spends time. Before their development, it is good to be sure of their necessity. The aim of the first part of this work is to study causes of inaccuracy and their influence on measurement results. To do this, we take measurements with a maximum of care on an I.G.B.T. and we simulate, one by one, causes of errors. This study allows to détermine some références mark up to choice equipment or to judge the necessity of corrections. In a second part, we study the I.G.B.T. modelling and, more generally, non-linear electrostatic four pôle modelling. By comparing measurements done on the I.G.B.T. with the results of simulation, we show influence of non-linear capacities of the I.G.B.T. on simulation.
