A self-balancing circuit to measure capacitance and loss conductance for industrial transducer applications

This paper describes a capacitance and loss conductance measuring circuit for the use in industrial transducers. The circuit is based on self-balancing principle and it is immune to stray capacitance. The balancing process is controlled by a micro-controller. The capacitance and loss conductance are represented by the digital feedback signals or by the combination of the feedback signals with the forward path signals. Experimental results show that the circuit has high resolution (0.04 fF) and good linearity (0.999).