Highly sensitive magnetic sensing method using magnetoresitance devices

A highly sensitive magnetic sensing method using magnetoresistance devices is proposed. An InSb magnetic sensing device was used in the feedback loop of a Hartley oscillator. The oscillation starts when the resistance of the InSb magnetic sensing device changes in the external magnetic field as the oscillation condition is fulfilled. We can detect the magnetic 1 or 0 signal, corresponding to oscillation or nonoscillation, respectively. Output response and error rate in our magnetic sensing for the detection of oscillation were invesitigated. As a result, a high output response of 1 V_pp was obtained even if the electric sensing current which flows into the InSb magnetic sensing device was 450 μA. The resistance change of more than 30 Ω is required in order to maintain an error rate of less than 10^-5. Therefore, this magnetic sensing method has potential application in highly sensitive magnetic sensors.