13 October 2008 A novel quasi-digital detection method of micro differential capacitance in micro-accelerometers
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Abstract
This paper proposed a novel method of sensing the weak differential capacitance change of Micro-Electro-Mechanical Systems (MEMS) accelerometer with sandwich structure. The detection circuit mainly consisted of frequency selective networks, Phase Locked Loop (PLL), logical gate and low-pass filter. The two elemental capacitances of differential capacitance respectively harmonic oscillated in two parameter symmetry resonance units. Beating wave represented when the two output signals with different frequency had passed the logical gate and low-pass filter in turn. The frequency of beating wave was proportional to the sensing differential capacitance. One of the most important aspects of using circuit resonance elements with MEMS technology was the elimination of analog voltage amplitude measurement used in conventional MEMS accelerometers. On the other hand, this method overcame the disadvantages of conventional mechanical resonance accelerometers, with frequency output and high Signal Noise Ratio (SNR), such as poor dynamic response, temperature drift, complex structure and large power dissipation. According to the numerical simulation results, the circuit resonance detector with PLL can reach high capacitance resolution: 10-16 F.
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Xing Song, Xing Song, Jiancheng Fang, Jiancheng Fang, Ranran Yi, Ranran Yi, Wei Sheng, Wei Sheng, } "A novel quasi-digital detection method of micro differential capacitance in micro-accelerometers", Proc. SPIE 7127, Seventh International Symposium on Instrumentation and Control Technology: Sensors and Instruments, Computer Simulation, and Artificial Intelligence, 712716 (13 October 2008); doi: 10.1117/12.806338; https://doi.org/10.1117/12.806338
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