提出了一種差動電容式傳感器的前置電路,基于電容/ 電壓轉換的原理,對微小電容變化量進行測量。電路輸出的直流電壓與差動電容變化量成線性關系,且能對偏差電容和電路的漂移進行自動補償。實驗表明,被測電容分辨力為8 f F , 靈敏度可達3. 82 ×1011 V/ F。實驗結果和理論分析具有良好的一致性。
關鍵詞: 電容式傳感器; 小電容測量; 線性電路; 電容/ 電壓轉換
Abstract : A prepositive circuit for differential capacitance transducers is proposed. It can be used to detect small capacitance changes based on capacitance to voltage conversion. The output dc voltage is a linear with the com2 plementary capacitance change and can be used to compensate for offset capacitance and drifts automatically. The experiment results show a good correspondence with the theoretical analysis. The resolution of the measurement of capacitance change is 8f F ,and sensitivity is 3. 82 ×1011 V/ F.
Key words : capacitive transducer ; low2capacitance measurement ; linear circuit ; capacitance/ voltage conversion