廉德钦,何常德,苗静,杜春晖,宛克敬,薛晨阳.基于交流电桥的动态微弱电容检测电路[J].电测与仪表,2012,49(7):89-92. LIAN De-qin , HE Chang-de , MIAO Jing , DU Chun-hui , YUAN Ke-jing , XUE Chen-yang.Micro Capacitance Measuring Circuit Based on AC Bridge[J].Electrical Measurement & Instrumentation,2012,49(7):89-92.
基于交流电桥的动态微弱电容检测电路
Micro Capacitance Measuring Circuit Based on AC Bridge
The Capacitive Micromachined Ultrasonic Transducers based on MEMS technology has developed.Under the action of ultrasound,the change of its effective capacitance is only fF-level and changes very fast,so measuring is very difficult.The half AC bridge capacitance detection circuit presented in this paper can convert the rapidly changing capacitance signal into voltage signal,and load the voltage signal into high-frequency sinusoidal excitation signal,then obtain capacitance variation through amplification,demodulation and filtering.The circuit effectively inhibits the influence of stray capacitance,and the linearity and stability of the circuit are good.The sensitivity can achieve 2.8mV/fF with 200kHz ultrasonic wave,and basically meet the needs of the micro capacitance change detection of the Capacitive Micromachined Ultrasonic Transducers.
