Design Of Interface Integrated Circuit Of Micro Fluxgate Magnetic Sensor

The miniature fluxgate sensor is a magnetometer device commonly used in the field of weak magnetic field measurement,especially in the fields of aerospace,marine navigation and topographic survey,etc.It has been widely favored.The miniaturization,integration and low power consumption of the system make the miniature fluxgate sensor a hot research direction.In this paper,based on the relevant basic principles of the miniature fluxgate sensor,based on the three-terminal fluxgate probe and the second harmonic selection method,a miniature fluxgate sensor interface circuit chip that can be used for the measurement of the three components of the ambient magnetic field is designed.This article completes the system modeling and simulation test of the fluxgate sensor,and analyzes the simulation results,and summarizes the relevant conclusions,which provides a reference for the specific implementation of the circuit;in the implementation of the excitation circuit,the ring oscillator is used as The signal source of the excitation circuit generates a local oscillator signal with a frequency of20 k Hz and a value of 0～5V.The frequency division circuit and the switching network are designed to process the local oscillator signal into a differential excitation signal with a frequency of 5k Hz and a control signal with a frequency of 10 k Hz;detection In terms of circuit implementation,a low-noise,high-gain preamplifier is designed in this paper.According to the second harmonic method,a band-pass filter circuit,a phase-sensitive detection circuit,and a low-pass filter circuit are constructed to form a second The detection path of the sub-harmonics is picked up,and the feedback circuit is used to connect the entire circuit to the closed-loop mode.This paper uses the BCD350 nm process to realize the design of each circuit module,and uses the Spectre simulator to simulate each link and the whole circuit,verifying that the circuit has good performance.When the three-terminal probe material is set to Permalloy,the saturation magnetic induction strength and relativepermeability refer to the typical value of Permalloy,the number of turns of one side coil is 1000,and the cross-sectional area of ??the magnetic core is 6mm2,these parameters are substituted The overall circuit is simulated in the probe electrical model,and finally it is concluded that the overall interface circuit is under the condition of 5V supply voltage,the sensitivity within the measurement range of±10000n T is 8.54 m V/μT,and the nonlinear error is about 0.06%.