A capacity measuring circuit includes a measuring voltage source configured to feed a sinusoidal voltage signal to a first terminal of a capacity to be measured so as to cause a temporal change in a charge stored on the capacity to be measured. The capacity measuring circuit additionally includes a delta-sigma modulator. The delta-sigma modulator is configured to receive a charge from a second terminal of the capacity to be measured and to provide a digital output signal which is dependent on a quantity of the charge received from the capacity to be measured. The capacity measuring circuit may be employed in a sensor system.