Research On Noise Suppression Of Tunnel Magnetoresistance Ocean Magnetometer

The magnetic tunnel junction(MTJ)sensors have the advantages of high sensitivity,low power consumption,low cost,and small size.They are widely used in medical,automotive,industrial and other fields.However,the disadvantage of tunnel magnetoresistive sensors is that they are affected by background noise and environmental noise.The impact is more serious,which limits its actual detection capabilities.In response to this problem,this article attempts to use the free layer flip technology to suppress the background noise of the tunnel magnetoresistive sensor,and considers the method of equivalent parallel connection of the sensor array to improve the signal-to-noise ratio.This process involves the suppression of the spatial background noise.Research,suppress the background magnetic field noise by the method of sensor array cancellation.Before for background noise for low frequency noise within the scope of the tunnel magnetoresistance sensor is analyzed,to understand the characteristics of the main noise in low frequency range and the possible reasons that noise,and then established the equivalent noise model of tunnel magnetoresistance sensor,determine the noise mainly comes from magnetic tunnel resistance device,lay the foundation for the next study.According to the characteristics of low frequency background noise of tunnel magnetoresistance sensor,the free layer flipping technique is used to reduce the noise.In order to realize the method of noise suppression by free-layer flip technology,the hardware system was firstly built,mainly including pulse generator module and sensor module.The pulse generator module realized the generation of bipolar pulse.The sensor module was compared with two different structures.Then,the modulation characteristics of the sensor are processed according to the free-layer flipping technology.The final results show that the free-layer flipping technology can suppress the low-frequency background noise of the tunnel magnetoresistive sensor,and the background noise can be reduced by about 6 times in the range of 1Hz.The method of sensor array cancellation processing is used to suppress spatial background noise.Simulation and experimental verification show that the method can effectively suppress spatial background noise.The method is verified by the actual underwater experimental data obtained from sea trials,and the cancellation process is improved according to the actual data,and the SNR is increased by about 10 d B.On the basis of the above,the principle of the method of improving SNR by equivalent parallel sensor array is verified.Under the condition of shielding spatial background noise,experiments show that this method can improve the signal to noise ratio.