A design of differential capacitance detection circuit

The application of distance differential capacitance sensors to measure micro vibrations is now widely witnessed in the field of earthquake engineering. However, the structure of detection circuits is correspondingly complex for the vibration signal is small. This design improved the situation by updating the switch device structure in switching phase-sensitive detection circuit. It is demonstrated by experiments that the new circuit has a wide measure range when the displacement of sensor is less than 0.295mm, the linearity is less than 1.2% and the sensitivity is about 9.524V / mm.