| In this thesis, three actively damped low noise MEMS microphones with vastly different feedback schemes were examined for their tolerance with respect to nonlinearity, to parameter uncertainties, and to an unmodeled parasitic component in the readout circuit. More specifically, simulations were used to analyze the ability of a linear analog feedback controller and sigma-delta control loop to robustly damp the resonant peak in spite of the nonlinearity of the capacitive transducer and parameter variation. The analog feedback controller was able to partially damp the resonance but the performance was limited by the linear operation region. The sigma-delta control loop was successfully able to damp the resonant peak for reasonable microphone variations. Additionally, circuits were designed for the sigma-delta control loop and the controllers for a robust capacitive sensing damping scheme. |
