Mems Micro-capacitance Sensor Detection Circuit Development

As an important branch of the intellectualized microcomputer electrical system series, the research and the manufacture technology of micro electric capacity type sensor is developed rapidly in the microminiaturization, multi-purpose in recent years. Since there are so many advantage; such as smaller in volume, light in weight , lower in power loss, and it is easy to integrate, the mechanical pressure and the accelerometer sensor has the most representation in the type of micro electric capacity sensor. Although this domain's research development greatly at present, but there are still many questions to be solve in practicality application.The micro electric capacity sensor acts as the signal detection and the transformation in the micro-machinery system, the performance of entire microcomputer electrical system decided by its operating performance, the stability, the reliability, and the test electric circuit is the key part in the micro electric capacity sensing. The research and the design which aims to the micro electric capacity test and transformation circuit work efficiently are the very significance in theory and the practical application.This article conducts the research in view of micro electric capacity examination switching circuit aspects and so on topology, performance index, interference rejection. Alternate current stimulation electric capacity - voltage transformation circuit is selected for the micro electric capacity detection after analysis the several current commonly used metering circuit structure. The analysis is also discussed in the test circuit theoretical, the anti-interference, and the error produce principle. The hardware of circuit system designed including sine signal prompting, AC amplifying, electric capacity - voltage transition, full-wave rectification, low-pass wave filtering and so on. In consideration of the value of micro-capacity's variation from pF to fF to test system, the ratio of circuit signal to noise request is definite high, thus, the micro-capacity test circuit's parameter in essential part is require optimization through the simulation and debugging from experiment. Finally, the test circuit was success pass though the experiment by simulation and debugging, the conclusion indicated that the circuit satisfies the requirements of design.