The Research Of Capacitance Silicon Micro-gyroscope Sense Signal Readout Circuitproperties

The silicon micro-gyroscope fabricated by micro-machining technology is an important kind of inertial sensor to measure angular velocity that is widely used in aerospace, vehicle and consumer electronics. Thanks to low cost, small size, easy integration and high reliability, capacitance silicon micro-gyroscope has been studied intensively this years. For capacitance silicon micro-gyroscope, the accuracy of silicon micro-gyroscope measurement is determined by sense capacitance signal readout. Thus capacitance silicon micro-gyroscope sense signal readout circuit is the essential content of high sensitive gyroscope research work.Based on silicon micro-gyroscope capacitance detection theory, this paper research on capacitance silicon micro-gyroscope sense signal readout circuit. After the contrastive analysis of typical sense capacitive readout circuit structure, charge amplifier was selected to be the core of differential modulation sense signal readout circuit. Then differential modulation circuit, demodulator circuit and filter amplifier circuit were designed for the real circuit, with their work principles and electrical properties analyzed. At last the circuit was optimized in component, parameter and PCB according to the imperfect circuit noise model.The circuit noise character was test by Agilent 35670 a dynamic signal analyzer with zero input. Through the circuit test, measurements results indicate the superior performance of the circuit, with a noise floor of-116.24 dBV/(?) and a capacitive resolution of 1.16×1910 F/(?), which can meet gyroscope high-precision test.