A simple method for measuring voltage dependent capacitance using TDR system

Measurement of circuit parasitic parameters, and evaluation of equivalent circuit models are needed for a noise analysis or a high-speed operation circuit design of power electronics circuit. Recently, TDR system is known as a technique of circuit parameter measurement. This paper proposes a TDR method for measuring the voltage dependent capacitance of power MOSFETs. This method can measure output capacitance Coss of MOSFETs on any DC bias voltage. In the experiment, Coss of MOSFETs with VPDS = 0 ∼ 350V is presented.