A Y-decoder includes a selection unit and a Y-MUX. The selection unit is coupled to the memory array for selecting the column lines. The Y-MUX is coupled to the selection unit for supplying a voltage to the selected column line. The Y-MUX includes a first switch, a second switch, a third switch and a fourth switch coupled in parallel. The first switch and the second switch are respectively for receiving a first shielding voltage and a second shielding voltage. The third switch and the fourth switch are respectively for receiving a first sensing voltage and a second sensing voltage.