A level shifting circuit includes a level shifting unit and an output buffer unit. The level shifting unit generates first and second output signals responsive to first and second input signals. The first and second input signals range between first and second voltage levels, and the first and second input signals are a first differential pair. The first and second output signals range between the first voltage level and a third voltage level greater than the second voltage level, and the first and second output signals are a second differential pair. The output buffer unit inverts the first and second output signals to provide third and fourth output signals, respectively. Duty ratios of the first and second output signals are determined based on delay times of the first and second input signals.