Patent ID: 8330492

Claim:
A semiconductor device comprising a first transistor, a second transistor, a third transistor, and a fourth transistor, wherein a gate and a first terminal of the first transistor are electrically connected to a first wiring, wherein a second terminal of the first transistor is electrically connected to a gate of the fourth transistor, wherein a gate of the second transistor is electrically connected to a second wiring, wherein a first terminal of the second transistor is electrically connected to a fourth wiring, wherein a second terminal of the second transistor is electrically connected to the gate of the fourth transistor, wherein a gate of the third transistor is electrically connected to a third wiring, wherein a first terminal of the third transistor is electrically and directly connected to the fourth wiring, wherein a second terminal of the third transistor is electrically connected to the gate of the fourth transistor, wherein a first terminal of the fourth transistor is electrically and directly connected to the fourth wiring, and wherein a second terminal of the fourth transistor is electrically connected to a fifth wiring.