Research On The Interface Circuit Of Magnetic Sensor And Its Application

Magnetic sensors,as a bridge from magnetism to electricity,have been widely used in recent years in consumer electronics,new energy vehicles,drones,industrial control,and biochemical detection.Nowadays people can convert magnetic field signals into digital signals for processing,the conversion process from magnetic sensors to digital signals becomes an essential part of the design.In the thesis,an FPGA-based magnetic field sensor system with the goal of being easily integrated into other digital systems has been designed.The main research contents are as follows:(1)The method of Analog-to-Digital Conversion in FPGAs without ADC chips,which based on the Sigma-Delta modulator theory,is discussed.This method has a low conversion rate,a high upper limit of accuracy,and does not take up many resources.These features make it easy to integrate into other FPGA-based digital systems.The MATLAB Simulink simulations of two common Sigma-Delta modulator structures were performed.One of them has been built using discrete components.(2)An FPGA board was designed ? fabricated,a three-stage digital filter was implemented in the FPGA.The SFDR of the Analog-to-Digital Converter part was tested separately,and reached 77.78 d B,approximately.(3)A simple interface circuit built by discrete components was designed for two common types of magnetic sensors,Hall sensor,and TMR sensor.Two PCBs were designed,fabricated ? tested.An OOT module in GNU Radio has been written to get the magnetic field information from the board.The signal processing is done by using the flowgraph.A demodulator of the Digital Lock-In Amplifier is simulated in GNU Radio.The results show the possibility that the magnetic field sensor system can be used in the Digital Lock-In Amplifier.