Fundamental Mode Orthogonal Fluxgate Magnetometer Applicable for Measurements of DC and Low-Frequency Magnetic Fields

Compatibility of low noise characteristic and offset stability is essential for a magnetometer to be applicable for measurements of dc and low-frequency magnetic fields. Fundamental mode orthogonal fluxgate (FM-OFG) magnetometer has advantages in its compact design and low noise characteristic, whereas its disadvantage is the offset drift which is unacceptably large for such measurement. An effective technique called bias switching has been proposed to suppress and stabilize the offset of open-loop FM-OFG magnetometers, yet when it is adopted with a feedback configuration to obtain better linearity, it increases noises attributed to the convergence process. In this paper, we present a design of sensor driving electronics of FM-OFG magnetometers to solve this problem and achieve compatibility of low noise and stable offset characteristics with a feedback configuration. The efficacy of the design was verified through various performance evaluations.