[en] A higher-order electromechanical sigma–delta modulator can greatly improve the signal-to-noise ratio compared with a second-order loop that only uses the sensing element as a loop filter. However, the electrostatic force feedback on the proof mass is inherently nonlinear, which will produce harmonics in the output spectrum and limits the total signal-to-noise and distortion ratio. High performance inertial sensors, which use sigma–delta modulators as a closed-loop control system, have strict requirements on the output signal distortion. In this paper, nonlinear
effects from the force feedback and pick-off circuits are analysed and a strategy for force feedback linearization is put forward which can considerably improve the signal-to-noise and distortion ratio. A PCB prototype of a fifth-order electromechanical modulator with a bulk micromachined accelerometer was used to demonstrate the concept.
Disciplines :
Electrical & electronics engineering
Author, co-author :
Dong, Yufeng
Kraft, Michael ; Université de Liège > Dép. d'électric., électron. et informat. (Inst.Montefiore) > Systèmes microélectroniques intégrés
Redman-White, William
Language :
English
Title :
Force feedback linearization for higher-order electromechanical sigma--delta modulators
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