A programmable capacitor for inductance measurements

Abstract

This paper describes a programmable capacitor intended for use as the reference impedance in an inductance measurement system. The capacitor is programmable from 1 pF to 39 μF with a resolution of 1 pF and consists of a parallel combination of commercially available capacitors with values that follow the Fibonacci series progression. This paper presents a novel calibration procedure for the programmable capacitor that uses an LCR meter performing only difference measurements and requires only 3 reference capacitance standards within the device's programmable range. Design details and major sources of error for the use of the capacitor in an inductance measurement system are also discussed.