Research On Horizontal Hall Plate And Its Application In 3-axis Magnetic Sensor

Magnetic sensors play an important role in various applications such as non-contact controllers.Distance,displacement,and angle information can be obtained by measuring the direction and strength of the magnetic field.Hall sensor has the advantages of high stability,low price,simple structure,and good compatibility with CMOS processes when compared with other magnetic sensors.The enormous popularity of Hall sensor drives researchers to develop the sensor in the direction of high sensitivity,low power consumption,and low offset.Research on Hall sensors,especially in the direction of three-axis Hall sensors,started relatively late in China and requires more attention to be paid.The main works of this thesis are as follows:(1)A finite element model of the horizontal Hall sensor has been developed.The current-biased horizontal Hall sensor is studied and its finite element model is developed using COMSOL Multiphysics software.A variety of different structures,such as square,rectangular,cross,and octagon shapes,of Hall plates are simulated and compared to explore the optimal design scheme.Final design of cross-shaped Hall plate with a widthto-length ration of 0.55 is proposed and obtained a current-related sensitivity of 161.6V/A/T and a voltage-related sensitivity of 0.061V/V/T.(2)A Verilog-A model and an electric interface of the horizontal Hall sensor are presented.Based on the design of the cross-shaped Hall sensor from the COMSOL simulation,a corresponding Verilog-A model is built and verified in Cadence.The current-spinning circuit based measurement system performs the function of amplifying the Hall signal and eliminating unexpected offset voltage from the Hall plate.(3)A new method to realize an IMC(Integrated Magnetic Concentrator)-based three-axis Hall sensor is proposed.By introducing the magnetic field amplification factor in the signal processing process,the inclination angle and absolute strength of the threeaxis magnetic field can be measured using only four horizontal Hall plates.Compared with the traditional structure,the proposed method doesn't need a permanent magnet as a reference.This thesis innovatively builds a finite element model of this IMC-based three-axis Hall sensor based on the horizontal Hall device COMSOL model.The magnetic field amplification factor is studied and the influence of several design parameters are simulated and compared.Finally,a three-axis sensor structure scheme is proposed and has achieved an accuracy of 0.8° and 1.2° for the magnetic field inclination angle.In addition,it is also expected that this thesis provides readers with a general method and a new perspective to design and optimize relevant works.