Work

GHz-Bandwidth Twin-Coil Magnetic Current Sensors for Compact Switching Circuits

Year: 2026

Type: article

Abstract: Accurate measurement of current switching transients in SiC and GaN power converters requires current sensors with bandwidths exceeding 100 MHz, along with high immunity, sensitivity, isolation, and usability. Magnetic coils are typically the least invasive type of sensor but can be challenging to design and may be unsuitable in high EMI environments. This paper explores the use of coreless twin-coil magnetic current sensors in compact power circuits with complex magnetic fields. A design method is presented to achieve the required bandwidth, immunity, and signal-to-noise ratio (SNR), guided by 2D gain and immunity plots to optimise orientation relative to adjacent currents. Equations for gain and bandwidth as functions of geometry are experimentally verified using a vector network analyser. The method is validated in two scenarios: individual gate current sensing on adjacent, parallel-connected power devices, and power loop current sensing on a 30 mm wide PCB trace with a closely spaced return path on an adjacent layer. The gate sensor achieves an SNR above 10, a 660 MHz bandwidth, and closely matches current sense resistor measurements. The power loop current sensor has similar accuracy to a commercial Rogowski coil. These results demonstrate removable high bandwidth AC current sensors that minimally impact compact, optimised circuits, and show promise for application in power modules.

Source: IEEE Transactions on Power Electronics

DOI: 10.1109/tpel.2026.3652644

Authors: Yushi Wang, Zhaobo Zhang, Renze Yu, Saeed Jahdi, Bernard H. Stark

Institution: University of Bristol

Language: English

Topic: Magnetic Field Sensors Techniques

Subfield: Electrical and Electronic Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: green

Funder: Engineering and Physical Sciences Research Council

Awards: High-Density Active Silicon Carbide Power Electronics: Enabling Responsive Power Conversion, High-Bandwidth Sensing for Wide-bandgap Power Conversion, Transforming Net Zero with Ultrawide Bandgap Semiconductor Device Technology (REWIRE)