Increasing the input common-mode range of a circuit which accepts differential signals as inputs. Such an increase may be attained by correcting an input signal at continuous levels or at 2 or more discrete levels) without changing the strength represented by the input signal. In an embodiment, the common-mode component of an input signal is measured, and a correction voltage proportional to the difference between the measured common-mode component and a reference voltage, is generated. The correction voltage is coupled to the input terminals of the differential circuit to correct for any deviations from a desired level of common-mode voltage at the input terminals of the differential circuit. The approaches are applied to a switched-capacitor differential amplifier used in a sample-and-hold portion of an ADC.