Experimental Comparison and 3D FEM Based Optimization of Current Measurement Methods for GaN Switching Characterization

Three high bandwidth current measurement methods to acquire fast switching transients with GaN HEMTs are compared. A 3D FEM (finite element method) simulation is used for analysis and optimization of a very low inductive SMD shunt. The focus is on the use of an FEM simulation in order to adapt the current measurement method to the requirements for GaN HEMTs characterization. The simulation results and optimizations are verified with experimental results. In conclusion, the optimized SMD shunt achieves a high bandwidth (> 500 MHz) with a very small additional inductance in the power loop.