PURPOSE: To suppress the occurrence of overshoot at the time of switching to shorten the settling time and to increase the operation speed by setting a first driving signal in accordance with characteristics of the first conduction type so that the high level of the signal is lower than the potential of a first power source or the low level is higher than the ground level.

CONSTITUTION: The first driving signal is constituted in accordance with characteristics of the first conduction type so that the high level of the signal is lower than the potential of the first power source or the low level is higher than the ground level. Consequently, the cross point between first and second driving signals outputted from first and second driving circuits 6 is set to the lower side (in the case of PMOS transistors) or the upper side (in the case of NMOS transistors) in comparison with conventional that. Thus, first and second switching transistors Q15 and Q16 are not simultaneously turned on/off, and fluctuation of a voltage Vx in an internal node X by simultaneous switching is smaller than conventional.