| The research of signal processing circuit of micromachined tunneling accelerometer is presented in this thesis, and the method of PID controller used to control the closed-loop feedback system is analyzed for exploration.Considering the impact of the parameters of sensitive component on circuit design, this research also explains the operating principle of the tunnelling accelerometer sensor and its interface circuitry. It focuses on the impact of some key parameters such as tunnel-top height and initial gap on detecting performance, proposes different requirements of the circuit design according to both package forms in the air or vacuum, and tests the parameters of structural and electrical of the formed sensors.One of the key points of the thesis is design signal processing circuit to collect weak tunnel current and output testing result, which will be expatiated in the third chapter. This part describes operating principle of the wholel circuit in detail. In I-V conversion module, it analyzes the differences between bias voltage stability and conversion accuracy due to two different I-V conversion methods, provides theoretical reference of choosing the amplifier by comparing available performance parameters, presents some measures such as noise shielded and current leakage prevent to improve the whole system performance.According to the detailed modeling and analyzing of feedback control system in the vacuum package, in order to meet vacuum packaged requirement of the sensitive components, the closed-loop feedback control system with PID is researched in view of the signal output oscillation in the low damping circumstances.After completing the online debugging of the sensor chip with its interface circuit, the acceleration static calibration and noise tests are carried out in a normal environment and low noise environment respectively. In the low-noise environment, the perfect result is presented with a special testing system for sensitivity test of tunneling accelerometer.
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