An interpolator includes interpolation cells. Each interpolation cell includes a first driving unit and a second driving unit. The first driving unit includes a first pulling-up circuit for selectively coupling an output terminal to a high voltage, a first pulling-down circuit for selectively coupling the output terminal to a low voltage, and a pair of first switches for selectively enabling/disabling the first pulling-up circuit and the first pulling-down circuit. The second driving unit includes a second pulling-up circuit for selectively coupling the output terminal to the high voltage, a second pulling-down circuit for selectively coupling the output terminal to the low voltage, and a pair of second switches for selectively enabling/disabling the second pulling-up circuit and the second pulling-down circuit. Driving capabilities of the first and second pulling-up circuits are not all equal, and/or driving capabilities of the first and second pulling-down circuits are not all equal.