Electrodes for microelectromechanical system microphones

A microelectromechanical system (MEMS) sensor comprising:

• a membrane;
• a membrane electrode formed in a portion of the membrane;
• a backplate situated parallel to the membrane and separated from the membrane by a gap;
• a backplate electrode formed in a portion of the backplate, wherein the membrane electrode at least partially overlaps the backplate electrode in a sensing region forming a sensing capacitor;
• and
• a sensing circuit coupled to the sensing capacitor and configured to sense motion of the membrane in response to acoustic pressure, wherein the sensing region is situated away from a point of maximum motion of the membrane in response to the acoustic pressure.

A microelectromechanical (MEMS) acoustic sensor comprising:

• a membrane;
• a membrane electrode formed in a portion of the membrane;
• and
• a backplate situated parallel to the membrane and separated by a gap, the backplate comprising:
• a first region of the backplate having formed therein first perforations of a first density;
• a second region of the backplate having formed therein second perforations of a second density, wherein the second density is greater than the first density;
• and
• a backplate electrode formed in a portion of the backplate,
• wherein a portion of the membrane electrode overlaps a portion of the backplate electrode in a sensing region forming a sensing capacitor, the sensing capacitor being configured to sense motion of the membrane in response to acoustic pressure,
• wherein the first region of the backplate encloses a point of maximum motion of the membrane in response to the acoustic pressure, and
• wherein the second region of the backplate is situated away from the point of maximum motion of the membrane in response to the acoustic pressure.