Research And Design Of The Linear Hall Effect Sensor ASIC

As an important branch of magnetic sensors,Hall sensors are widely used in many fields,such as Notation defence technology,automotive electronics,industrial automation,transportation and so on.The rise of wearable device,electronic toys and other emerging consumer electronics industry has also opened up a new application market for Hall sensors,promoting the development of Hall sensor technology and the upgrading of related products.With more auto industry-related companies moving to the domestic market in the next few years,the future of Hall sensors is limitless.The application requirements of Hall sensor are increasing day by day and the market potential is huge.Based on this background,this thesis designs a linear Hall sensor ASIC.The main research results and innovations are as follows: 1.The chopper stabilization technique is designed to eliminate the offset voltage of Hall element.Combined with modulation circuit,low noise,low offset chopper amplifier,the offset signal is separated from the magnetic field voltage in frequency domain,and the DC offset is modulated into a high frequency signal,which is filtered by subsequent low pass filter circuit.Finally,an accurate magnetic field voltage is guaranteed achieving higher sensing precision.The simulation results show that the offset voltage is restrained by 90%.2.The function of adjusting sensitivity dynamically is realized.User can program the chip by VCC and VOUT pins,interact with the highly integrated EEPROM and store calibration values into it.The internal digital circuit calculates the calibration values and generates a corresponding adjustment signal,which achieve dynamic configuration of sensitivity and static output voltage.The adjustment range of sensitivity is 0.6 ? 14.8mV/G,the initial static output voltage is set at 1/2 of the power supply voltage,and its typical adjustment range is 2?3V.3.A digital compensation system architecture is designed to improve sensitivity temperature characteristic.When the operating temperature changes relative to the room temperature,the internal processor of the chip calculates the correlation coefficient stored in the EEPROM according to the temperature compensation formula,and generates a compensation signal to change the gain of the operational amplifier in the analog signal path,achieving temperature drift compensation for the sensitivity of the Hall element.The test results show that the temperature drift of Hall sensor sensitivity is controlled within ±3% in the range of-40??150?.When the sensitivity is less than 8.5mV/G,the linearity within 1% of the error can be guaranteed.4.The key circuit modules of Hall sensor are designed and verified by simulation.The 1.2V voltage is generated by reference voltage module,the temperature drift of reference voltage is 8.32ppm/?,which means superior temperature characteristic.The Regulator provides 5V stable operating voltage for other circuit modules in the chip,with high power supply rejection ratio,and anti-reverse circuit structure within this module is designed to prevent polarity reversal.The functions of POR & UVLO modules are resetting the chip during supply voltage power-on and latching chip when under-voltage,protecting the chip from damage.Low-noise chopper operational amplifier amplifies the magnetic field voltage,while the internal chopper modulator is used for dynamic matching to reduce the noise of operational amplifier.Hall sensor is designed and simulated by using EDA tools such as Schematic edit,Spectre of Cadence and so on.After completing layout design,the IC is taped out based on 0.18 um BCD process.Temperature control system,digital oscilloscope,signal generator and other testing devices of Thermonics,Rigol and other companies are used to complete the test of samples.The simulation results and test data show that functions of the chip are normal and the parameters meet the design requirements.