Application of the flux bending effect in an active flux-guide for low-noise planar vector TMR magnetic sensors

Abstract

A concept of a planar vector magnetic sensor comprising in-plane tunnel magnetoresistivc (TMR) sensors and an active flux-guide (AFG) was introduced in this work. The AFG redirected the magnetic flux at high-frequency benefiting a vertical detection capability and suppressing the field noise of the TMR at low-frequency measurement. The vertical sensitivity of 19.5 V/T was close to the in-plane sensitivity of 19.2 V/T. In addition, the 1-Hz field noise was suppressed from 6 nT/√Hz down to 0.4 nT/√Hz. The flux bending effect of the AFG was also verified by the angular measurements with the angular deflection was found to be about 50°. It revealed that the vertical field component was certainly detected by the in-plane sensor, and the proposed method was a feasible approach for the development of the low-noise planar vector magnetic sensor.