A folding analog-to-digital converter (ADC) is disclosed. The folding ADC includes a reference voltage generating unit generating a plurality of reference voltages, a low power analog pre-processing unit including a plurality of folders, each of which compares a voltage level of an analog input signal with a corresponding reference voltage of the plurality of reference voltages to generate a pair of differential folded outputs, a comparison unit that compares outputs of the low power analog pre-processing unit to output a digital signal, and an encoding unit that converts an output of the comparison unit into a binary code signal.