A circuit comprises first, second, third, and fourth transistors. The first transistor has a first current electrode, a control electrode for receiving an input signal, and a second current electrode. The second transistor has a first current electrode coupled to the second current electrode of the first transistor for providing an output signal, a control electrode coupled to the control electrode of the first transistor, and a second current electrode coupled to a first power supply voltage terminal. The third transistor has a first current electrode coupled to a second power supply voltage terminal, a control electrode, and a second current electrode coupled to the first current electrode of the first transistor. The fourth transistor has a first current electrode coupled to the control electrode of the third transistor, a control electrode coupled to the control electrodes of the first and second transistors, and a second current electrode coupled to the control electrode of the first transistor.