Techniques and circuits are described for approximation of the differential capacitance of a capacitive sensor to, among other things, optimize device operation and power consumption. In particular, feedback techniques are utilized for measurement and approximation of the differential capacitance of the capacitive sensor. In accordance with the disclosure, the capacitance approximation value for a test cycle preceding a given test cycle is utilized to reduce the number of iterations to be performed in a continuous series of test cycles. The capacitance approximation value for the given test cycle is reported as being equivalent to that of the preceding test cycle if the variance between the selected capacitance and the unselected capacitance is less than or equal to a first predefined value.