Nonlinear distortion compensation for capacitive MEMS microphones

A non-transitory computer-readable storage medium comprising stored instructions, the instructions when executed by a processor of a device, causing the device to:

• receive a signal corresponding to an input sound pressure detected by a capacitive microelectromechanical system (MEMS) microphone, wherein the capacitive MEMS microphone includes an active capacitance and a parasitic capacitance;
• determine that a nonlinear relationship exists between the signal and the input sound pressure;
• determine, based on the signal, an input parameter associated with the active capacitance and the parasitic capacitance;
• determine an output signal based on the input parameter, wherein the output signal and the input sound pressure have a linear relationship;
• compensate the signal based on the determined output signal so that the compensated signal has the linear relationship with the input sound pressure;
• and
• output the compensated signal as an output corresponding to the input sound pressure.

An audio system comprising:

• a capacitive microelectromechanical system (MEMS) microphone configured to receive a signal corresponding to an input sound pressure, wherein the capacitive MEMS microphone includes an active capacitance and a parasitic capacitance;
• a controller configured to:
• determine that a nonlinear relationship exists between the signal and the input sound pressure;
• determine, based on the signal, a normalized displacement (B) of a movable electrode in the active capacitance corresponding to the input sound pressure;
• determine an output signal based on the normalized displacement, wherein the output signal and the input sound pressure have a linear relationship;
• and
• compensate the signal based on the determined output signal so that the compensated signal has the linear relationship with the input sound pressure;
• and
• a speaker configured to output the compensated signal as a sound output corresponding to the input sound pressure.