Research On Key Technologies Of Angle Detection ASIC Based On Magnetoresistance Effect

With the development of sensor technology,angle sensors are widely used in consumer electronics,industrial control and automotive electronics,especially in the measurement of motor rotor angle.The magnetoresistance angle sensor uses the magnetoresistance effect and the corresponding ASIC(Application Specific Integrated Circuit)to complete the magnetic angle detection.Based on Tunnel Magnetoresistance(TMR),the ASIC of angle detection is studied in this thesis.The main contents include:1.The principle of magnetic angle detection based on TMR effect is analyzed,and an overall scheme of angle detection based on TMR is proposed.The key modules in the scheme include TMR sensor element,signal conditioning circuit,angle calculation unit,the interface,power supply and clock modules.The digital decimation filter,non-ideal error and CORDIC algorithm principle in the system are mainly studied and discussed.2.The Sigma delta ADC in angle detection ASIC is studied.Based on Simulink,the simulation model of sigma delta modulator and digital decimation filter is built.The decimation factor of digital decimation filter can be 128,256,512 or 1024.The output end of the filter adopts the "rounding" method for truncation processing,which improves the signal to noise ratio of the system.Based on this,0.18 μm BCD process has completed the design of angle detection Sigma delta ADC chip,and the digital circuit part involves the design and verification of digital decimation filter,register,SPI slave and ADC calibration module in the chip,and has successfully completed the chip.3.The angle detection system is studied.Based on Simulink,the simulation model of the angle detection system is built,mainly including the modeling of the angle sensor body and the non-ideal error calibration compensation module.After calibration,the error of angle calculation is controlled within 0.2 °.The prototype of the angle detection system is built based on FPGA.The CORDIC algorithm is used to calculate the angle value,whose results are analyzed by MATLAB.The results show that the angle detection resolution of the system can reach 16 bits,the error at low speed(0～3000 rpm)is within± 1 °,and is within ± 1.5 ° at high speed(5000～20000 rpm).