A Simple Stray-Free Capacitance Meter by Using an Operational Amplifier

A simple operational amplifier circuit known as a charge amplifier has an advantage of measuring capacitance independent of stray capacitance. Capacitance down to 0.03 pF could be experimentally measured with ease and the theoretical limit of measurement is discussed. Also the direct measurement of the electrostatic induction coefficients of a system of conductors by the circuit is introduced.