Damping Analysis of Asymmetrical Comb Accelerometer

Abstract

The resonance phenomenon is suppressed by adjusting the damping of the comb accelerometer structure to widen the frequency bandwidth of the capacitive accelerometer. The capacitive accelerometer with asymmetrical combs, fabricated with DRIE and anodic bonding, is presented. The damping category of the accelerometer is introduced, in which the squeeze-film damping coefficient and the damping ratio factor are detailed. The damping ratio factor of the accelerometer, measured by a vibration method, is 0.17. The damping ratio factor of the optimized structure is calculated of 0.15 to 0.18 with the change of experiential modulus C from 25 to 30, theoretically.

Prediction of Gap Asymmetry in Differential Micro Accelerometers

“…Gap asymmetry pertains to the disproportion between the capacitive gaps of two capacitors that form a differential sensor. Its occurrence causes the calibration line to deviate from its origin and forms zero bias output; that is, the output voltage of a force-balanced accelerometer is no longer zero under zero acceleration input [ 19 , 20 ]. Consequently, the measurement ranges in the positive and negative directions differ, and feedback circuit parameters cannot be established in a similar manner as those designed under ideal conditions.…”