A semiconductor device includes a first transistor and a second transistor connected in series between a first voltage source and a second voltage source. A diode is connected between a gate of the first transistor and the second voltage source. A capacitor is connected to the gate of the first transistor. A first driver is connected to the gate of the first transistor through the capacitor. A second driver is connected to a gate of the second transistor. A threshold voltage of the second transistor is higher than a threshold voltage of the first transistor.