| 摘要 |
A circuit for minimizing electrostatic forces in capacitance-based sensor circuits. A sensor includes a movable mass (10) that forms the center electrode of two differential capacitors, a sensing differential capacitor (24) and an actuator differential capacitor (52). The other two electrodes (18, 20, 46, 48) of each differential capacitor are fixed. Oppositely phased high-frequency carrier signals are applied to the fixed electrodes of the sensing capacitor and biasing signals are applied to the fixed electrodes of the actuator capacitor (52). When a force is applied to the sensor, the capacitance of the sensing capacitor changes and the carrier signal, with its amplitude and phase modulated in accordance with the magnitude and direction of the force, appears on the movable mass (10). The signal on the mass (10) is fed back to the fixed electrodes of the sensing capacitor to minimize electrostatic forces between the electrodes of the sensing capacitor. Using a separate negative feedback loop, a signal is fed back to the mass to generate electrostatic forces between the mass and the fixed electrodes of the actuator capacitor to restore the mass (10) to its original position. |
