| GMR sensors play an important role in industrial control,automotive electronics,medical and environmental detection and other fields.It has become more popular than other magnetic sensors because of its advantages,such as high precision,high sensitivity and low energy consumption.However,it's sensitivity changes with the change of temperature that restrict the application of high precision measurement.In order to expand the application range of GMR sensor and improve the measurement precision of GMR sensor,so it's highly important to compensate the sensitivity of GMR.Based on the structure and principle of spin valve GMR sensor,this thesis introduces the temperature characteristics and build the mathematical model between temperature and sensitivity.Summarizing the method of temperature compensation for sensors,the Mix-signal integrated circuit is implemented which based on the standard CMOS process.There have six parts in this system,such as spin valve sensor model,temperature sensor,data conversion,instrumentation amplifier,unit inverting amplifier,programmable resistor array.The temperature sensor senses the variation of environment temperature and the data converter convert the output of temperature sensor into digital signal to control the programmable resistor which connected with instrumentation amplifier,then changes the gain of instrumentation amplifier to compensate the output of GMR sensor.Establishing the SPICE model of spin valve GMR sensor and design the compensation system based on the CSMC Mix signal process.Simulated in the Cadence spectre environment with 5V supply voltage.The simulation shows that the temperature coefficient is /678 ppm ? after compensating,but the temperature coefficient is /2498 ppm ?without compensating.Although the compensation method and the result of compensation is Specific,the compensation method and the structure of the circuit system are universal to the GMR sensor. |
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