基于ASIC芯片的微小电容测量电路研究

Ultra-small Capacitance Sensing Circuit Based on a Piece of ASIC

基于一款专用集成电路芯片(ASIC)HT133实现了一种微小电容测量电路。该电路具有高分辨率、高抗干扰性、偏置调节能力和模拟、数字信号两种输出模式等特点。文中详细论述了测量电路的实现以及电路的抗干扰措施,并通过测定一组微小电容验证了电路的性能。实验表明,电路分辨率达0.5 fF,非线性度8.67%。该电路在各种电容式传感器特别是微机电系统(MEMS)传感器中有广泛的应用前景。

A circuit based on a piece of Applications Specific Integrated Circuit （ASIC） HT133 for sensing ultra-small capac- itance is presented. It has some prominent features such as high resolution, high anti-interference ability, offset adjustment ability and both analog and digital signal output modes. Implementation of every module and means of noise limitation are described detailedly. An experiment measurement of a series of small capacitances is performed. Results show that the circuit has very high performance with resolution of 0.5 femtofarad （0.5 × 10^-15 farad） and nonlinearity of 8.67 %. A basis for this ASIC to be applied in capacitive sensors especially micro-electro-mechanical system（MEMS） sensors is provided.