A Hybrid Magnetic Current Sensor With a Dual Differential DC Servo Loop

Journal article (2023)

Authors

A. Jouyaeian Electronic Instrumentation - EEMCS
Q. Fan Electronic Components, Technology and Materials - EEMCS
Udo Ausserlechner Infineon Technologies AG, Austria
Mario Motz Infineon Technologies AG, Austria
K.A.A. Makinwa Microelectronics
Research Group
Electronic Instrumentation (EEMCS) (TU Delft)
Copyright: © 2023 A. Jouyaeian, Q. Fan, Udo Ausserlechner, Mario Motz, K.A.A. Makinwa
DOI: https://doi.org/10.1109/JSSC.2023.3307471
Sensors DSL High resolution Temperature compensation Bandwidth Capacitors Magnetic tunneling Coils Hybrid current sensors Magnetic current sensing Servomotors Contactless sensing Dc servo loop (DSL)
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Published Date

2023

Language

English

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Faculty

Electrical Engineering, Mathematics and Computer Science

Department

Microelectronics

Research Group

Electronic Instrumentation

Abstract

This article presents a hybrid magnetic current sensor for contactless current measurement. Pick-up coils and Hall plates are employed to sense the high and low-frequency fields, respectively, generated by a current-carrying conductor. Due to the differentiating characteristic of the pick-up coils, a flat frequency response can then be obtained by summing the outputs of the coil and the Hall paths and passing the result through a 1st-order low-pass filter (LPF). For maximum resolution, the LPF corner frequency (2 kHz) is set such that the noise contribution of each path is equal. To suppress the coil-path offset without the use of large ac coupling capacitors, an area-efficient dual dc servo loop (D3SL) is used. This effectively suppresses the coil-path offset, resulting in a total offset of 73 μT , which is mainly dominated by the Hall path. Fabricated in a standard 0.18-μm CMOS process, the current sensor occupies 3.9 mm2 and draws 7.1 mA from a 1.8 V supply. It achieves 43 mA resolution in a 5 MHz bandwidth, which is 1.5 × better than the state-of-the-art hybrid sensors. It also achieves the lowest energy efficiency FoM (3.5 ×) among CMOS magnetic current sensors.