Study On Noise Decreasing Of MEMS Capacitive Accelerometer And Electrostatic Self-excited Driving Of MEMS Resonont Devices

What this thesis mostly research on can be divided into two parts, one is the study on decreasing the noise of MEMS accelerometer and its circuit, and the other is the design of the electrostatic self-excited drive circuit applied to resonant devices.For the sake of better application to petroleum exploration, the resolution and the other properties of MEMS accelerometer and its circuit are improved on the base of former MEMS accelerometer which has been developed. First, the principle of former MEMS accelerometer and its circuit is analyzed. By comparing the noise of different circuits' forms and analyzing the noise source of MEMS accelerometer and its circuit, some measures are taken to improve the resolution of MEMS accelerometer which is from former 0.01m/s~2 to latter 0.001m/s~2. So it is proved that these measures can improve the resolution effectively.Electrostatic self-excited drive circuit is applied to resonant devices because it can search the resonance frequency precisely and automatically. When the resonance frequency drifts because of the changing process, temperature or environment, this circuit can easily catch the frequency. It can also search the resonance frequency of different devices and stabilize the amplitude. By analyzing the principle of electrostatic force, it is found that there are two modes of electrostatic driving force including vertical and parallel directions. The circuit can finally drive accelerometer automatically by designing, simulating and testing. Then it is transplanted to apply to gyroscope by transforming some circuit's parameters. So it can be proved that this circuit can be applied to some different resonant devices just by regulating the phase of closed loop to 2kπ, adjusting the cut frequency of LPF and changing the gain of...