Wideband Tunneling Magnetoresistance Current Sensor With Dual-Parallel Current Trace Utilizing the Skin Effect

In highly integrated switching circuits and power electronic converters, noncontact wideband current sensors are typically required for monitoring operational status. However, the magnetic field distribution of printed circuit board traces is influenced by the skin effect as the current frequency increases, which, in turn, affects the frequency characteristics of the sensor. In this study, we propose a dual-parallel current trace structure, which, through simulation analysis and experimental verification, utilizes the characteristics of the skin effect to enhance the equivalent magnetic induction detectable by the tunneling magnetoresistance (TMR) current sensor near 1 MHz, thereby improving its frequency response. Compared to traditional single-path current trace, the dual-parallel current trace structure demonstrates superior performance in terms of frequency bandwidth, current sensitivity, and resolution. Based on this novel current trace structure, we design and demonstrate a wideband TMR current sensor with a frequency range of dc-1.5 MHz, which provides a 50% improvement in bandwidth compared to traditional TMR sensor with single-path current trace. Furthermore, the sensor exhibits a full-scale error of no more than 0.4% within the 2.9 A rms range, a minimum resolution close to 5.4 mA, and excellent waveform tracking capability.