Design, Modeling and Simulation of a Closed-Loop Controller for a Dual Backplate MEMS Capacitive Microphone

This work reports the design, modeling and simulation of an all electrostatic, analog closed-loop controller for a dual backplate MEMS capacitive microphone. In this work, a Simulink model which incorporates the key dynamics of the sensor, interface circuit, and sense and feedback non-linearities has been developed. Sinusoidal and step response of the open and closed loop systems were simulated. The closed loop system has a loop gain of 38 dB and a phase margin of 42deg. The simulations predict that the maximum diaphragm displacement for a \m drop test is attenuated from 6.2 pm to 7.1 times 10
^-2
pm (38 dB attenuation).