Reducing Measurement Error in Capacitive Readout Circuits Based on Weakly Coupled Resonators

Abstract

A recently proposed method for measuring minute changes in capacitance based on weakly coupled resonators has been examined for its sensitivity with respect to unwanted resonant frequency changes. This sensitivity has been compared with the conventional capacitance measurement method based on the capacitance to frequency conversion. It has been analytically shown that both sensitivities are nearly equal but with opposite signs. This has led to a new hybrid capacitance measurement method to reduce the error by at least an order of magnitude. The analytical results have been validated by various simulations and experimental measurements.