Design of a Resonant Miniature Electrostatic Field Sensor with Feedback Driving and Detection

The paper presents a new design of resonant miniature electrostatic field sensors (EFS) based on surface micromachining process. With a phase and an amplitude closed loop feedback control, the sensor can be adjusted automatically to operate at its resonant frequency in despite of the temperature influence. For minimizing the capacitive feedthrough, a feedback detecting loop is utilized in the design. The digital concept of the new electronics for EFS aims to eliminate the additional noise and especially temperature drift yielded by analog components. Based on a digital lock-in amplifier, the main function of the designed electronics has been realized. We achieve a lower nonlinearity of 1.8% (end-point-straight-line) at resonant frequency (4.13 kHz) in measurement the range of (0~10kV/m for our primary EFS