| abstract |
An operation speed of a circuit is improved. A first transistor has a function of setting the potential of the gate of the first transistor to a value at which the first transistor is turned on, the first terminal being connected to the gate of the first transistor. A second transistor, a third transistor having a function of setting the potential of the gate of the second transistor to a value at which the second transistor is turned on, and having a function of floating the gate of the second transistor; A fourth transistor having a function of setting the potential of the gate of the transistor to a value at which the second transistor is turned off. With such a structure, the potential difference between the gate and the source of the second transistor can be maintained at a value larger than the threshold voltage of the second transistor, so that operation speed can be improved. [Selection diagram] Fig. 1 |