Imaging device, operating method thereof, and electronic device

An imaging device comprising:

• a first photoelectric conversion element;
• a second photoelectric conversion element;
• a first transistor;
• a second transistor;
• a third transistor;
• and
• a fourth transistor;
• wherein a cathode of the first photoelectric conversion element is electrically connected to one of a source and a drain of the first transistor,
• wherein an anode of the second photoelectric conversion element is electrically connected to one of a source and a drain of the second transistor,
• wherein the other of the source and the drain of the first transistor is electrically connected to the other of the source and the drain of the second transistor,
• wherein the other of the source and the drain of the first transistor is electrically connected to a gate of the third transistor,
• wherein one of a source and a drain of the third transistor is electrically connected to one of a source and a drain of the fourth transistor,
• wherein the first transistor and the second transistor comprise an oxide semiconductor in an active layer, and
• wherein a first signal which is input to a gate of the first transistor is different from a second signal which is input to a gate of the second transistor.