Research On And Design Of Low Noise Linear Hall Sensor

As sensing elements for Io T applications,sensors are widely used in various fields such as industrial production and daily life.Hall sensor can be directly or indirectly used in various magnetic detection systems because of its unique characteristics and excellent performance,which has huge prospects in global market.With the continuous development of end product applications,Hall sensor becomes more miniaturized,intelligent,and integrated in the future,and needs to have the characteristics of low noise,low temperature drift and high sensitivity,which puts higher requirements on the design of Hall sensor.Based on the current Hall sensor technology,this paper aims to reduce the overall noise of the sensor,and implements a linear Hall sensor with low noise performance.It integrates a high sensitivity Hall disk and a low noise interface readout circuit,and it's taped out finally.The main research results and innovations of this article are as follows:1.For the problems of offset voltage and 1/f noise in Hall element and amplifiers,this paper improves the circuit of the traditional instrumentation amplifier structure,and combines the quadrature rotating current method and chopper stabilization technology to eliminate the existence offset and 1/f noise of the Hall element and readout circuit,and designs a low-noise interface readout circuit.The Hall small signal voltage is magnified by the preamplifier and variable gain amplifier.The chopper technique is realized through the modulation circuit,chopper amplifier and switched capacitor notch filter,which reduces the overall noise of the sensor.2.For the temperature change of the Hall sensor sensitivity,a method for temperature compensation of bias current of Hall element is proposed to reduce the temperature drift of the Hall plate.At the same time,a segmented temperature linear interpolation method is designed,and the gain coefficient of the readout circuit is corrected according to the test result of the sensor temperature drift to ensure the stability of the sensor in the entire operation temperature range.3.To realize the adjustable sensitivity and static output voltage of Hall sensor,it is proposed to integrate EEPROM memory array inside the chip,design stable and reliable programming logic,reasonably arrange the gain setting coefficient of the readout circuit and the setting coefficient of the output common mode voltage,which offer various sensitivity and static output voltage options.4.For the noise problem introduced by the power supply and the ground wire,a regulator circuit with positive and negative power supply and high power supply rejection ratio is proposed to provide power for other circuit modules inside the chip.The low noise,low temperature drift and Brokaw structured bandgap reference circuit provides accurate reference voltage values,and the UVLO and POR circuits with hysteresis are designed to prevent damage to the chip due to power supply changes.Based on the above research work,the design of the low-noise linear Hall sensor IC in this article uses 0.18?m 60V BCD process.Circuit design,simulation,and layout are completed by the Cadence platform.Tapeout and sample test are carried out finally.Simulation and test results show that its power consumption is about 15m A,programmable sensitivity range is0.6?14.8m V/G under±15V power supply.The output noise voltage of the sensor within the entire bandwidth is 6.2m V_P-P under the typical application conditions.After temperature compensation,the sensor sensitivity's drift within the operation temperature range of-40oC?150oC is lower than±3%.Therefore,the low-noise linear Hall sensor IC designed in this paper can be applied to high-precision magnetic field measurement occasions.