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为将陀螺结构引入到闭环驱动电路的仿真系统中,建立了与微机械陀螺结构等价的电学模型.微机械陀螺闭环驱动电路基于电荷泵锁相环技术,用低噪声跨阻放大器代替传统的电荷放大器实现I-V转换,有效避免了电荷放大器在实现I-V转换时所产生的随陀螺固有频率变化而变化的相位误差.用基于CCCII+技术的有源电阻代替无源电阻,大大降低了电路的噪声,并且提高了电路的集成度.仿真结果表明,微机械陀螺结构的固有频率为2.7 kHz,陀螺结构在驱动方向位移的相位滞后于驱动方向驱动力相位90°;在50μA的偏置电流下,有源电阻阻值为250 kΩ,在工作频率下的噪声为0.037 fV2/Hz,大大低于无源电阻的噪声.闭环接口电路实现了在陀螺固有频率下的自激振荡.
In order to introduce the gyro structure into the simulation system of the closed-loop drive circuit, an equivalent electrical model with the micromechanical gyro structure is established.Microcyrical gyro closed-loop drive circuit is based on the charge-pump phase-locked loop technology and uses low-noise transimpedance amplifier instead of the traditional The charge amplifier realizes IV conversion and effectively avoids the phase error caused by the change of the natural frequency of the gyroscope generated by the charge amplifier when the IV conversion is implemented.The passive resistance based on CCCII + technology is adopted to reduce the noise of the circuit greatly, The simulation results show that the natural frequency of MEMS gyroscope is 2.7 kHz, the phase of the gyrostructure in the driving direction lags behind that of the driving force in the driving direction by 90 °. At the bias current of 50 μA, The source resistance is 250 kΩ and the noise at the operating frequency is 0.037 fV2 / Hz, which is much lower than the passive resistance noise. The closed-loop interface circuit enables self-oscillation at the natural frequency of the gyro.