A novel gate charge measurement method for high-power devices

Conventional gate charge (Qg) measurement methods require high-power power supply that covers test condition of both Drain-Source voltage (Vds) and Drain current (Id). Such measurement system is not only expensive but also dangerous due to its enormous energy. In addition, its measurement accuracy and repeatability are not good enough due to the nature of its dynamic way of evaluation. We propose a new Qg measurement method that doesn´t require high-power power supplies. The proposed method delivers desired Qg curve, corresponds to high-power measurement condition, from Qg curves measured at low-power conditions. We demonstrate the proposed method with commercial MOSFETs and IGBTs and validate the delivered curves match sufficiently with the curve measured by conventional method. This paper also discusses the theory of Qg curve in detail and reveals how Qg curve is calculated from other characteristics such as capacitance-voltage (CV) and current-voltage (IV) characteristics with its nonlinearity considered.