MEMS vibrating beam accelerometer with built-in test actuators

A method of testing of a microelectromechanical system (MEMS) vibrating beam accelerometer (VBA), the method comprising:

• applying a force to a proof mass of a MEMS VBA in a direction of motion of the proof mass, wherein the proof mass is located between a first proof mass actuator electrode and a second proof mass actuator electrode, wherein the first proof mass actuator electrode is positioned adjacent to a first side of the proof mass and the second proof mass actuator electrode is positioned adjacent to a second side of the proof mass, wherein the first side of the proof mass is opposite the second side of the proof mass, wherein the first proof mass actuator electrode and the second proof mass actuator electrode comprise opposing parallel plates, wherein the first proof mass actuator electrode and the second proof mass actuator electrode are separate from a first resonator;
• detecting, by either of the second proof mass actuator electrode or the first resonator, a motion of the proof mass due to the applied force, wherein the first resonator is mechanically coupled to the proof mass;
• and
• connecting, subsequent to the detecting a motion of the proof mass due to the applied force, the first and second proof mass actuator electrodes to ground, wherein the first and second proof mass actuator electrodes are configured to be prevented from applying a force to the proof mass when connected to ground.

A system comprising:

• a microelectromechanical system (MEMS) vibrating beam accelerometer (VBA) comprising:
• a proof mass;
• a first resonator mechanically coupled to the proof mass;
• a second resonator mechanically coupled to the proof mass, wherein the first resonator and the second resonator are arranged with opposing scale factors;
• a first proof mass actuator electrode separate from the first resonator and second resonator and positioned adjacent to a first side of the proof mass and having an air gap between the first proof mass actuator electrode and the proof mass;
• a second proof mass actuator electrode separate from the first resonator and second resonator and positioned adjacent to a second side of the proof mass and having an air gap between the second proof mass actuator electrode and the proof mass, wherein the first side of the proof mass is opposite the second side of the proof mass, wherein the first proof mass actuator electrode and the second proof mass actuator electrode comprise opposing parallel plates configured to apply a force to the proof mass in a direction of motion of the proof mass, wherein the proof mass is located between the first and second proof mass actuator electrodes,
• wherein the second proof mass actuator electrode is configured to sense a motion of the proof mass and output a signal corresponding to the sensed motion of the proof mass, wherein the first and second proof mass actuator electrodes are configured to be connected to ground, wherein the first and second proof mass actuator electrodes are configured to be prevented from applying a force to the proof mass when connected to ground;
• and
• processing circuitry configured to:
• cause the first proof mass actuator electrode and the second proof mass actuator electrode to apply the force to the proof mass in the direction of motion of the proof mass;
• receive the signal corresponding to the motion of the proof mass in response to the applied force sensed by the second proof mass actuator electrode;
• and
• determine the motion of the proof mass based on the received signal.