Patent ID: 7093478

Claim:
A method of calibrating an accelerometer comprising: a. providing the accelerometer comprising: i. a substrate; ii. a mass suspended over the substrate and movable relative to the substrate, the mass including a movable electrode; iii. a first fixed electrode suspended over the substrate and not movable relative to the substrate; iv. a second fixed electrode suspended over the substrate and not movable relative to the substrate, the movable electrode and the first and second fixed electrode forming a differential capacitor; v. an excitation and readout circuit coupled to the movable electrode and to the fixed electrodes to provide an amplified signal; vi. an actuator, the actuator suspended over the substrate, the actuator displacing the mass by electrical means when activated; and vii. a spring suspended over the substrate connected to the mass, the spring and the actuator laid out such that a dimensional relationship is established between the actuator and the spring; b. measuring the resonant frequency of the mass; c. displacing the mass with the actuator; d. measuring the change in the amplified signal; and e. calculating the sensitivity of the accelerometer including calculating an acceleration equivalent to displacing the mass with the actuator wherein calculating the acceleration includes calculating a function of the resonant frequency, the form of the function determined by the dimensional relationship between the actuator and the spring.