MEMS accelerometer self-test using an active mobile mass deflection technique

A method for self-testing a microelectromechanical system (MEMS) accelerometer sensor having a mobile mass and at least one sensing capacitor and a rotor node, comprising:

• during a reset phase of a sensing circuit coupled to the at least one sensing capacitor, applying a test signal including a pulse to the at least one sensing capacitor, said test signal configured to generate an electrostatic force which produces a physical displacement of the mobile mass corresponding to a desired acceleration value;
• applying an AC drive signal to the rotor node, wherein the AC drive signal has a low voltage level during assertion of each pulse for the test signal;
• and
• during a read phase of the sensing circuit, sensing a variation in capacitance of the at least one sensing capacitor due to the physical displacement of the mobile mass and converting the sensed variation in capacitance to a sensed acceleration value.

A method for self-testing a microelectromechanical system (MEMS) accelerometer sensor having a mobile mass and at least one sensing capacitor, comprising:

• cyclically repeating a sensing circuit reset phase and a sensing circuit read phase over a self-testing time period;
• generating a test signal that includes a series of pulses over said self-testing time period;
• during each sensing circuit reset phase, applying a pulse of said test signal to the at least one sensing capacitor in order to generate an electrostatic force which produces a physical displacement of the mobile mass corresponding to a desired acceleration value;
• selecting a number of pulses within the series of pulses and a duty cycle of the pulses within the series of pulses in order to set a magnitude of the physical displacement of the mobile mass;
• and
• during each read phase of the sensing circuit, sensing a variation in capacitance of the at least one sensing capacitor due to the physical displacement of the mobile mass and converting the sensed variation in capacitance to a sensed acceleration value.

A method for self-testing a microelectromechanical system (MEMS) accelerometer sensor having a mobile mass and at least one sensing capacitor and a rotor node, comprising:

• cyclically repeating a sensing circuit reset phase and a sensing circuit read phase over a self-testing time period;
• generating a test signal that includes a series of pulses over said self-testing time period;
• applying an AC drive signal to the rotor node, wherein the AC drive signal has a low voltage level during assertion of each pulse for the test signal;
• during each sensing circuit reset phase, applying a pulse of said test signal to the at least one sensing capacitor in order to generate an electrostatic force which produces a physical displacement of the mobile mass corresponding to a desired acceleration value;
• and
• during each read phase of the sensing circuit, sensing a variation in capacitance of the at least one sensing capacitor due to the physical displacement of the mobile mass and converting the sensed variation in capacitance to a sensed acceleration value.