A DC Error Self-Correcting Circuit for the Capacitive Micromachined Gyroscope

Micromachined gyroscope always contains two groups of capacitors, one is the driving capacitor, which is used to drive the micromachined gyroscope, to make sure the gyroscope could oscillate along the driving direction. The other is so called the sensing capacitor, which used to detect the displacement along the sensing direction, in order to detect the input angle velocity. Since there are some imperfections during the machining process, the static value of the driving capacitor and sensing capacitor always have some variations. These variations would cause some bad effects in the integrated circuit. In this paper, the variations of driving capacitor and sensing capacitor are analyzed based on the principle of integrated circuit. It is shown that the effect caused by driving capacitor variation would be cancelled in the signal processing, but the driving capacitor variation could cause a DC error signal at the output node of the first LPF in the integrated circuit. This DC error would distort the desired signal at the output node of the amplitude amplifier. So that a DC error self-correcting circuit is designed, both the simulation results and the testing results show that DC error could be self-corrected by this additional circuit.