Abstract: This paper describes use of USB interfaced multi-source DC power supplies to measure the I-V characteristics of high current, high power devices, specifically Power MOSFETs and Power Diodes. The LabView GUI program we developed enables the user to run the measurement, automatically, over the user specified current and voltage range while protecting the device from excessive currents and overheating via current and power limits also specified by the user. The LabView runtime window indicates the progress of the measurement time with a highlighted horizontal bar graph display and plots the drain I-V characteristics of the device in real time as the data is gathered. At the conclusion of the measurement an Excel compatible file is created for further evaluation, interpretation, graphing of the data, and for SPICE parameter extraction . Power MOSFET devices, to measure their I-V characteristics under a PC’s control, require a power supply with a minimum of two channels which can be controlled by a PC via a serial, or a GPIB, or a USB interface. Our experiments were conducted with a Keithley 2230-30-1 Triple Power Supply unit which has a USB interface. Maximum measurement ranges of voltage and current are limited only by the power supply at hand, not by the software. Our power supply had three channels, Channels 1 and 2 rated at 30V, 1.5Amp maximum, and a Channel 3 rated at 6V, 5.0 Amp maximum.
The power diode version of the program also gives the option of semi-log plotting of the diode I-V data in real time for the user to estimate a PN-junction diode's forward ideality factor and saturation current directly on the screen.
This is the first demonstration of using USB interfaced affordable power supplies instead of expensive source-measure units (SMU's) to measure the I-V characteristics of high-power semiconductor devices. Because of its simple and inexpensive hardware requirements, the system is perfectly suitable for use in the undergraduate electronics laboratories for instruction as well as being a tool in industrial and research laboratories for the product testing and characterization of high power semiconductor devices. The system can also adapted to measure the I-V characteristics of solar cells  and solar panels, and high-power Bipolar Junction Transistors (BJTs), as well.
 Guvench, M.G., "SPICE Parameter Extraction from Automated Measurements of JFET and MOSFET Characteristics ...," Proc. ASEE, s.1659, vol.1, pp.879-884, 1994
 Guvench, M.G., Denis, A.M., and Gurcan, C. "Automated Measurement of I-V Characteristics of Large Area Solar Cells …," Proc. ASEE, s.2531, 2003
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