Method and apparatus for measuring the change in capacitance values in dual capacitors

Abstract From the Canadian patent

A method and apparatus for calculating a ratio R, having a first capacitance value, C1 in inverse relation to, a second capacitance value C2, where C1 and C2 are the, capacitance values of a first capacitor and a second capacitor respectively. The first and second capacitors each have an independent electrode and share a common electrode. An AC voltage is applied to the common electrode producing first and second AC current signals at the two independent electrodes. A dual switched-capacitor integrated circuit and two current to frequency converters respectively convert the first and second AC current signals to first and second frequency signals having values f1 and f2. A microprocessor …