Measurement of Voltage-Dependent Capacitance Using a TDR System

The measurement of circuit parameters and the evaluation of equivalent circuit models are necessary for noise analysis or high-speed operation circuit design for power electronics circuits. Recently, time domain reflectometry (TDR) has emerged as a technique for measuring circuit parameters. This paper proposes a TDR method for measuring the voltage-dependent capacitance of a power MOS-FET. This method can be used to measure the output capacitance C-oss of a MOSFET for any DC bias voltage. The C-oss of a MOSFET with V-DS = 350 V was measured in an experiment, while the datasheet gives values of C-oss only for V-DS values in the range of 35 to 100 V. (C) 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 181(3): 31-38, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21289