Design And Research Of Low 1/f Noise Tunnel Magneto Resistance Accelerometer

Accelerometers are very important sensors and have been widely used in many different situations.However,in many precision measurement applications,the normal accelerometers like capacitive,piezoelectric and piezoresistive accelerometers are still difficult to meet the sensing requirements.Moreover,the sensing mechanism,structural design and manufacturing process of these accelerometers are highly mature,so it is very difficult to further improve their performance.At the same time,Tunnel Magneto Resistance?TMR?is a new kind of magnetoresistance with many advantages including high resistance change rate,large linear range,low power consumption and so on.Compared with other traditional sensing mechanisms such as capacitance,piezoelectricity and piezoresistance,TMR has the special advantages in low cost and high sensitivity measurement.Therefore,the development of low-cost and high-performance accelerometer based on TMR has the very high research potential and market space.In this research,a new TMR accelerometer is proposed,which can realize the acceleration sensing with low 1/f noise.Firstly,a novel TMR accelerometer structure design integrated with acceleration sensing and 1/f noise reduction is proposed and analyzed both in theory and simulation.By the analysis of the vibration theory and magnetic field theory,the force-magnetic-electric coupling model is built.Based on this model,the linear relationship between input acceleration and output voltage is also obtained,which proves that this design can realize the acceleration sensing.For modulation,after the analysis of modulation and demodulation theory,a modulation method based on the biased magnetic field is proposed using the high frequency resonant soft magnetic film.In theory and simulation,it is proved that the low frequency magnetic field signal can be modulated to the high frequency signal and the 1/f noise can be reduced.The experimental researches of this TMR accelerometer are carried out after the theoretical analysis and simulation.The acceleration sensing experiment without/with modulation are tested respectively,using the original designed experimental platform.In the acceleration sensing experiment without modulation,it is proved that the TMR accelerometer prototype can realize the acceleration sensing,and the sensitivity is 8.2 m V/m?s^-2.In the experiment with modulation,different modulation materials are tested,and the modulation ability of high-frequency resonating soft magnetic material film is clarified.More importantly,it is found that through modulation,the low-frequency signal such as 1.5Hz?3.5Hz and 7Hz can be modulated to187.5Hz/190.5Hz,185.5Hz/192.5Hz,182Hz/196Hz high-frequency signal.By the power spectral density analysis,the noise level of TMR accelerometer is reduced obviously and the 1/f noise of TMR is reduced by 10 times theoretically.Moreover,it has the potential to reduce1/f noise to the lower lever with higher natural frequency resonator.Finally,the residual signals in the experiment are analyzed,and the influence of zero drift error and modulation error is found,which shows the research direction for the next step.This research proposed a novel structural design and a novel modulation method of TMR accelerometer to realize the low 1/f noise acceleration sensing,which will be helpful to fill the empty of recent researches about TMR accelerometers.This study will also be helpful to exploit the potential of TMR sensors and make them more practicable.