Semiconductor device

A semiconductor device comprising:

• a first transistor comprising a first gate and a second gate;
• and
• a source follower circuit electrically connected to the first transistor, the source follower circuit comprising a second transistor and a third transistor,
• wherein the second transistor and the third transistor are connected in series,
• wherein the first gate is electrically connected to the second gate through the source follower circuit,
• wherein the second gate is electrically connected to one of a source and a drain of the second transistor and one of a source and a drain of the third transistor,
• wherein a channel formation region of the first transistor is provided between the first gate and the second gate,
• wherein in a first period during which a first voltage with which the first transistor is turned off is supplied to the first gate, a control voltage is supplied to the second gate,
• wherein in a second period during which a second voltage with which the first transistor is turned on is supplied to the first gate, a third voltage is supplied to the second gate, and
• wherein the second voltage is different from the third voltage.