A level shifter including a transistor that can be formed through the same process as a display portion is provided. A semiconductor device serves as a level shifter including transistors having the same conductivity type. The semiconductor device includes a so-called MIS capacitor in which metal, an insulator, and a semiconductor are stacked as a capacitor for boosting an input signal. Since the MIS capacitor is used, the gate-source voltage of a transistor for generating an output signal can be increased. Thus, boosting operation to generate the output signal can be performed more surely.

A signal channel includes at least one first signal line positioned in a first signal layer and at least one second signal line positioned in a second signal layer. The first signal layer extends in a first horizontal direction. The second signal layer extends along a second horizontal plane parallel to the first horizontal plane and spaced apart from the first horizontal plane along a vertical direction orthogonal to the first and second horizontal planes. The first signal line includes a first coupling segment and the second signal line includes a second coupling segment. The first coupling segment at least partially overlaps the second coupling segment along the vertical direction. The first and second coupling segments are positioned to form a greater degree of capacitive coupling between the first and second coupling segments than a degree of capacitive coupling formed between other segments of the first and second signal lines.

A signal channel includes at least one first signal line positioned in a first signal layer and at least one second signal line positioned in a second signal layer. The first signal layer extends in a first horizontal direction. The second signal layer extends along a second horizontal plane parallel to the first horizontal plane and spaced apart from the first horizontal plane along a vertical direction orthogonal to the first and second horizontal planes. The first signal line includes a first coupling segment and the second signal line includes a second coupling segment. The first coupling segment at least partially overlaps the second coupling segment along the vertical direction. The first and second coupling segments are positioned to form a greater degree of capacitive coupling between the first and second coupling segments than a degree of capacitive coupling formed between other segments of the first and second signal lines.