Design And Implementation Of Low Noise Voltage Reference And System Integration

With the increasing development of MEMS(Micro Electro Mechanical System),the application of MEMS acceleration sensor is very extensive with its unique performance advantages.There is a huge demand in the field of seismic exploration,automobile safety,navigation system,virtual reality etc.As the current research and application of silicon micro accelerometer,the capacitive MEMS accelerometer has been developed rapidly.The main components are MEMS acceleration sensor and readout circuit.It is necessary to design a high-performance weak signal detection circuit to put the attention on the advantage of the MEMS acceleration sensor due to the relatively low sensitivity because of the limitations of the potential factors.Voltage reference is the key,and its accuracy determines the maximum performance of all circuit modules.In practical design,how to suppress the non-ideal factors,including noise,is one of the key problems that needs to be solved urgently.It is very important to design and optimize the overall performance of critical voltage reference circuit module for MEMS accelerometer,which means minimizing the non-ideal factors to ensure the performance of the whole system.The paper is to solve the above problem by adopting chopper stabilization technology to design and tape-out,which is based on standard 0.5-?m CMOS process.The study of the voltage reference chip will be done as following aspects.Firstly,a self-adjusted voltage reference is designed,including the cascade structure of low-noise bandgap,folded cascode structure of positive/negative reference voltage circuit and two-phase non-overlapping clock.Secondly,combining the larger area of the input differential pair and chopper stabilization technology can yet be regarded as a common way to minimize the noise of amplifier.Thirdly,the test results show that all the indexes meet the expected requirements,and the noise performance has been improved.The corner frequency can been guaranteed about 3(?),and low-frequency noise(3(?))can reach to-140 dBV/ (?).In addition,the reference chip is integrated into the whole servo chip to improve the noise performance of the whole chip,and the system noise is reduced from-131 dBg/ (?) to-134 dBg/ (?),the minimum noise can be achieved with-140 dBg/ (?).