Theory of fluxgate sensor: Stability condition and critical resistance

This article established a useful method of solving the state equation of fluxgate sensor in which only basic detection circuit parameters were used. The solution of the equation was given, and the stability of the solution as well as critical resistance was discussed carefully. We also introduced stability condition of fluxgate by an inequality, the physical meaning of this inequality was discussed by simplifying it with maximum energy transfer condition. Experiments on different fluxgate sensors were performed, and the results show good agreements with calculation results.