An electronic device includes a photodiode, a first transistor, a second transistor, a third transistor and a capacitor. The photodiode has a first terminal and a second terminal. The first transistor has a control terminal used to receive a reset signal, a first terminal coupled to the second terminal of the photodiode, and a second terminal. The second transistor has a control terminal coupled to the second terminal of the photodiode, a first terminal and a second terminal. The third transistor has a control terminal used to receive a row selection signal, a first terminal coupled to the second terminal of the second transistor, and a second terminal. The capacitor has a first terminal coupled to the second terminal of the photodiode, and a second terminal coupled to the second terminal of the first transistor.