Excitation Frequency Effect of Differential Capacitance Transducer for Equivalence Principle Test

We discuss effects of the excitation frequency in an ac bridge differential capacitance transducer for the equivalence-principle test on the frequency-dependent characteristics of a practical operational amplifier, the thermal noise limitation, and stray-immune. Basic requirements of choosing the excitation frequency of the ac bridge capacitance transducer are given based on the three effects, which are significant for designing a capacitance transducer and choosing proper electric elements.