| The anisotropic magnetic sensor is based on the anisotropic magnetoresistance effect,including linear sensor and switch sensor.The anisotropic magnetic switch sensor chip fabricates by the anisotropic magnetic Wheatstone resistance bridge and integrated circuit in monolithic integration.It can optimize switching performance as well as replace imported chip.Firstly,this thesis introduces the history of anisotropic sensor,the development trend at home and abroad,as well as the value of making switch chip.Secondly,it introduces the whole circuit design of the anisotropic magnetic sensor switch chip and the working mode of the two modules.Then it optimizes the circuit on the basis of the original circuit as well as simulation in detail.Next,it sets up the high-low temperature test platform and magnetic working point test platform,then analyzes the test results.At last,it concludes the whole paper.This thesis is based on HGBD180GE0G CMOS technology,cooperated with Chengdu Cross-chip Company.We optimize the internal structure and circuit of the chip on the basis of the original design,which composed of six modules is as follows,Amplifier,Comparator,Regulator,Logic control,Output driver and Electro-Static discharge.The weak small signal is amplified by the Amplifier unit firstly,then the trigger and release switch adjustment action is realized by dynamic threshold adjustment.This thesis focuses on the optimization design of three sub-modules:Amplifier unit,Comparator unit and Regulator unit.In this thesis,a sinusoidal signal is used to simulate the signal generated by the magneto-resistive bridge.The results are as follows,（1）In standby mode,the turn off current of the whole circuit is as low as 12μA,which greatly reduces the power consumption of the chip.（2）The average power consumption of the whole sensor is very low,about 9.828μW.（3）The average start-up time is less than 4μs.The chip is taped out according to the design.We test the magnetic working points of the chip respectively under normal temperature as well as high and low temperature environment.The magnetic working point BOP is±10 GS,BRP is±5Gs under normal temperature.The input voltage range of the circuit is 1.8V～5.5V,the working temperature range is-40℃～85℃,and the working frequency is 50Hz.When the power supply voltage is 5V,the current consumption is about 2.4μA,and the average power consumption is 12μW,achieving the design goals.We come up with the new idea in this thesis that applies dynamic threshold adjustment to Amplifier unit and Regulator unit.We start earlier research on integrated AMR sensor chip,which is of great significance to the localization of high-end chips. |
