Magnetic Detector Based on GMI Effect of Amorphous wire

The giant magneto-impedance (GMI) effect of amorphous wire and its affecting factors were analyzed. Magnetic impedance (MI) element was designed with a special structure. So the difficulties of complex negative feedback circuit and winding double circuits on amorphous wire were solved. High frequency current pulse generator, signal preprocessing circuit and digital signal processing module were designed. Thus a low magnetic field detector was realized. The sensor and the detector were tested in laboratory. The experiment results proved that the sensor had good linearity at the magnetic field range from -3 Oe to +3 Oe. The sensitivity reached 65 mv/Oe and the sensor had well temperature stability. The magnetic field resolution can reach 50 mu Oe and small magnetic target can be detected.