Using Current Surface Probe to Measure the Current of the Fast Power Semiconductors

With the advantage of high bandwidth and small insertion impedance, a current surface probe (CSP) used to measure switching current waveforms is presented in this letter. Its transfer impedance is characterized and validated by measuring an IGBT switching current that is compared with those obtained with a current probe and a Hall effect current probe. Furthermore, by comparing with a current shunt to measure a GaN-HEMT switching current, it is shown that CSP is able to measure a switching current of a few nanoseconds, while it brings no influence on transistor voltage waveform measurement. The obtained results show that the use of CSP brings little parasitic inductances in the measurement circuit and it does not bring the connection of the ground to the power converter.