单载波调制型加速度计差分电容检测电路

摘要

单载波调制型差分电容检测电路是为满足微机械加速度计高线性度、高分辨率的需要而设计的,本文给出了检测电路的原理图,分析了寄生电阻、电容模型,从理论上证明该电路可有效消除寄生电阻和电容的影响,并推导了各关键功能模块的传递函数;此外,从电路的各个局部环节研究了会对电路性能造成影响的因素,包括放大电路的噪声源、载波信号稳定性、两路电荷放大器一致性、调制信号与参考信号相位同步等.经理论推导,通过改进和避免不利因素的影响即可保证电路的稳定性,适用于微机械加速度计检测领域.%The single-carrier modulation-type detection circuit is designed for the high-linearity,high-resolution of micromechanical accelerometer.In this paper,a circuit diagram is proposed.A model of parasitic capacitances and parasitic resistances is analyzed.It can be proved that the circuit can effectively eliminate the affect of parasitic capacitances and parasitic resistances.And the transfer functions of some important parts are presented.Moreover,the factors affecting the performance of the circuit are discussed,including amplifier noise sources,carrier wave stability,bi-amplifier consistency,modulate signal and reference signal phasic synchronization.Finally,it is concluded that the theoretical deduction and the improvement of bad factors can ensure the stability of the circuit.Therefore,the circuit is adapted to the micromechanical accelerometer detection.