A study of a high-resolution linear circuit for capacitive sensors

Abstract—A circuit for capacitance measurements is described. The circuit permits offset capacitance compensation using a dc voltage. The electronic circuitry with its testing is described. The output voltage is a linear function of the capacitance measured. Experimental data show good agreement with values predicted by the linear formula. Experiments show it is possible to measure capacitance changes with a resolution of a few femtofarads (fF). Index Terms—Capacitive sensor, femtofarads (fF), linear cir-cuit, low-capacitance measurement, offset compensation. I