Evaluation of a Low-Cost Wide Bandwidth Current Shunt for Characterization of Wide Bandgap Semiconductor Devices

Characterizing the switching losses of wide bandgap semiconductor devices requires wide bandwidth measurement equipment with the smallest possible insertion inductance added to the commutation path by the current sensor. A common current measurement approach is using low-cost off-the-shelf SMD resistors and measure the voltage drop. This SMD shunt approach has a limited bandwidth due to parasitic inductances. In this work, an evaluation of such a low-cost current shunt is performed. The influences and constraints that limit the bandwidth are investigated. The design of a compensation network and the resulting bandwidth improvement are examined. Based on the theoretical discussion, a compact current shunt is designed, that allows a simple integration into the commutation path while adding a low insertion inductance. The measurement results show, that the common measurement approach can reach a bandwidth of several hundred MHz if the design constraints are met and can be further extended by a compensation network.