Automatic Big Data Acquisition of Electrical Parameters in Wide Bandgap Devices

This paper presents an automatic big data acquisition experiment platform dedicated for online monitoring of Vth and Rds, on of GaN HEMTs. A new circuit topology combining power cycling test and double pulse test (DPT) together is proposed for measuring Rds, on and Vth. Gate driver signals are used to trigger two oscilloscopes to continuously and automatically store data. A quasi Vth online monitoring circuit has been implemented using fast comparator to monitor turn on transient of GaN devices. A hot plate has been used to preheat device under test (DUT), so the initial temperature in each cycle can be controlled. At the beginning of each cycle, DSP gives a double pulse signal to DUT and the platform is working in double test mode. So Vtk can be acquired at the same junction temperature. After that, the platform changes to power cycling test mode through controlling super junction MOSFET to turn on/off and also sending turn on/off signals to power supply. In order to make sure Rds, on is recorded at the same junction temperature in each cycle, Rds,on should be calculated at the beginning moment of the first cycle power cycling test. After 10 cycles of power cycling test, there should be a long cooling period before starting the next DPT. In this way, Vth can be acquired at the same junction temperature. The whole experiment process is controlled by DSP, so it can operate automatically and acquire big data efficiently.