The Study And Implementation Of A Hall Sensor Chip

A Hall sensor is widely used in automotive and industrial applications,because of its advantages of good electrical isolation,wide measurement frequency range and capability of being fully integrated in a standard CMOS process.However,the design of Hall sensor faces the challenges of sensitivity drifting and DC offset,limiting its applications in high accuracy measurement situations and wider range of current detection.This paper mainly studies how to eliminate the two limitations in Hall sensor chip.This thesis presents a Hall sensor microsystem with continuous sensitivity auto-calibration and offset voltage cancellation.With a spinning current technique,the external voltage,reference voltage and offset voltage are modulated,after that a programmable gain amplifier is applied to implement sensitivity adjustable,at the same time there are three parallel demodulators for extracting the three different signals to be dealt with respectively.First,the microsystem has its behavioral-level simulation in MATLAB to verify its stability and functional.What's more,the system-level MATLAB model can guide the circuits design.In order to simulate the Hall plate and reference coil in EDA software,resistors,capacitors,current control voltage source and clock generator are applied to model its function,the model is implemented in Verilog-A.Finally,the digital-analog co-simulation with AMS has verified the feasibility of the circuit-level design.This chip has been designed and taped out using XFAB XH035 3.3V process,the area of layout is 12.25mm~2.According to the measurement,at room temperature,the range of the magnetic field detection of the chip is-104.1mT~83.1mT,the linearity is less than 1%,the biggest sensitivity is about 10V/T,the output of offset voltage is about 10mV.The chip can realize the basic function for current detection.