Development Of Multicore Magneto-Impedance Sensor For Stable Pico-Tesla Resolution

We investigated the noise from amorphous wire magneto-impedance elements in a CMOS pulse sensor circuit and clarified the average current bias effect for low-noise magneto-impedance sensor operation. In order to raise the signal-to-noise ratio (SNR), a single-core head and multicore head were compared. We showed that the noise floor of the four-core head magneto-impedance sensor is lower than 1 pT/Hz(1/2) for the frequency range of 20 to 500 Hz. This result will be useful for designing a high SNR magneto-impedance sensor based on amorphous wire in combination with a CMOS pulse circuit.