Research Of Ring-Down Based ASIC Techniques For Micro Silicon Oscillating Accelerometer

Compared with traditional accelerometers,silicon micro-resonant accelerometers have the advantages of small size,low power consumption and strong anti-interference ability,and have become a research hotspot in the field of accelerometers.At present,most of the driving circuits of silicon micro-resonant accelerometers are realized based on the self-oscillation mode,and at the same time,additional temperature measuring components are used to compensate for temperature.With the deepening of research,it is found that the circuit in this mode will introduce 1/f noise error,phase-shift error and temperature hysteresis error,which restricts the low frequency stability of the accelerometer.Aiming at the above-mentioned problems in the self-oscillation mode,this paper has carried out the research on the measurement and control method of the silicon micro-accelerometer ASIC based on the Ring-Down mode.The main research work of the paper is as follows:First,the analysis of the silicon micro-resonant accelerometer ASIC system designed by the research group is carried out.The structure and principle of the system are studied.On this basis,the 1/f noise error,phase-shift error and temperature hysteresis error of the above circuit are further analyzed.In view of the above-mentioned three kinds of errors,the source and influence mechanism of the errors are studied,and the limitations of the existing error suppression schemes are explained at the same time;Then,the new circuit design based on the Ring-Down principle is carried out.Through the analysis of the Ring-Down mode,the specific suppression principle of the three kinds of errors is explained.In order to verify the suppression effect of the program on the above-mentioned errors,specific circuit design and hardware implementation of the measurement are carried out,the Ring-Down mode driving circuit is built using analog discrete devices,and the Ring-Down mode control and error suppression algorithm are realized by FPGA.The rationality of the circuit parameter selection is verified by circuit simulation;Next,research on the new error suppression algorithm based on the Ring-Down principle is carried out.The low-noise frequency extraction algorithm is designed to achieve the suppression of 1/f noise error and phase-shift error;the quality factor extraction algorithm is designed to achieve the suppression of temperature hysteresis error.In order to combine the two algorithms,an algorithm fusion scheme is proposed.Aiming at the amplitude coupling problem introduced by the fusion process,a self-compensation scheme of Duffing effect is proposed.In order to further reduce the power consumption and size of the system,ASIC is designed to implement the above algorithm;Finally,the function verification experiment and low-frequency error suppression experiment of the new scheme are carried out.Firstly,the functional completeness of the new circuit is verified through experiments;then,experiments are designed to explore the suppression effect of the measurement and control system on 1/f noise error,phase-shift error and temperature error.Experiments show that for 1/f noise,the scheme based on the RingDown principle reduces the bias instability from 3.39μg to 2.539μg;for phase-shift error,it is verified that the Ring-Down operating mode is not sensitive to phase-shift;for the temperature error,compared with the temperature measurement method based on the external temperature sensor,the temperature measurement method based on the quality factor reduces the bias stability in the full temperature range from 5.6mg to 2.1mg.