Universal Capacitive Sensors and Transducers Interface

The universal interfacing integrated circuit for direct capacitance-to-digital and capacitance-to-frequency (period, time interval)to-digital conversion suitable for various capacitive sensing elements is newly presented in the paper. Measurement results have successfully verified the functions and performance of the proposed circuit. The capacitance range is from 50 pF to 100 mu F. The worst case relative error for reported results is not more than +/- 0.7 %. Any capacitance-to-frequency converters can be also connected to the designed universal sensors and transducers interfacing circuit. The relative error for the further frequency-to-digital conversion is constant in the whole frequency range and not exceeds +/- 0.0005 %.