A High-Bandwidth Current Measurement Method Using an Integrated Rogowski Coil with an Inverse FIR Filter

In fast hard-switching devices, switching losses are a dominant part compared to all other losses in semiconductors. A difficult challenge is to accurately measure the source current of GaN HEMTs with only a minor influence on the commutation loop. This paper presents a solution for this by inserting an integrated Rogowski coil with an additional inductance of only about 1 nH. The design is very simple, solely modifications of the PCB layout are required. The bandwidth of the Rogowski coil can be increased to 1 GHz with an inverse FIR filter. As an example, the effect of different gate resistors on switching losses is shown in this paper.