Sensitivity adjustment apparatus and method for MEMS devices

摘要

A microelectromechanical (MEMS) microphone includes a MEMS motor and a gain adjustment apparatus. The MEMS motor includes at least a diaphragm and a charge plate and is configured to receive sound energy and transform the sound energy into an electrical signal. The gain adjustment apparatus has an input and an output and is coupled to the MEMS motor. The gain adjustment apparatus is configured to receive the electrical signal from the MEMS motor at the input and adjust the gain of the electrical signal as measured from the output of the gain adjustment apparatus. The amount of gain is selected so as to obtain a favorable sensitivity for the microphone.

主权项

1. A microelectromechanical (MEMS) microphone comprising:
a MEMS motor, the MEMS motor including at least a diaphragm and a charge plate, the MEMS motor configured to receive sound energy and transform the sound energy into an electrical signal; a gain adjustment apparatus, disposed on an integrated circuit and coupled to the MEMS motor, the gain adjustment apparatus comprising: an input configured to receive the electrical signal from the MEMS motor; an output; an amplifier configured to provide an output voltage at the output based upon a gain provided by the amplifier and the electrical signal; and a plurality of switchable capacitors, each of the plurality of switchable capacitors configured to be selectively connected to the input; wherein selective connection of the plurality of switchable capacitors to the input causes a sensitivity of the MEMS microphone to be within a predetermined specific target sensitivity range for the MEMS microphone; and wherein the plurality of switchable capacitors attenuate the output based at least in part upon a capacitance of the MEMS motor, a capacitance of the plurality of switchable capacitors that are connected to the input, and a capacitance of the integrated circuit.