200 MHz PCB Rogowski Coil Current Sensor for WBG Switching Applications

Current sensors based on PCB-integrated Rogowski coils offer a low-cost, high-performance solution, but are often optimized towards a narrow frequency band. To accurately reproduce both high frequency switching, as well as low frequency components in order to minimize droop issues, very broadband measurement is required. This work presents an improved PCB Rogowski coil current sensor for rectangular conductors, which utilizes distributed series and parallel resistors to dampen parasitic resonances and extend the bandwidth in the high frequency range with negligible impact to gain. Combined with advanced integration circuitry including a low frequency feedback loop, flat gain spanning more than six decades is achieved, enabling usability for very fast switching transients with long pulses containing low-frequency contents. The circuitry also enables DC restoration of the signal, making the sensor both useful for transient and steady-state measurements.