Fingerprint identification system and electronic device

An electronic device, wherein the electronic device comprises:

• an operating circuit;
• and
• a fingerprint identification system, coupled to the operating circuit, and the fingerprint identification system comprising:
• a plurality of first pixel circuits, a first pixel circuit in the plurality of first pixel circuits forming a contact capacitance with a finger;
• a first sensing circuit, coupled to the first pixel circuit, for sensing the contact capacitance and outputting a first output signal, wherein the first output signal contains a big signal component and a small signal component, and the small signal component correlates with a change amount of the contact capacitance, and the big signal component comprises a signal component influenced by parasitic capacitance, temperature and/or noise;
• at least one second pixel circuit;
• a second sensing circuit, coupled to a second pixel circuit of the at least one second pixel circuit, for outputting a second output signal, wherein the second output signal is equal to the big signal component;
• and
• a differential amplifying circuit, coupled to the first sensing circuit and the second sensing circuit, for amplifying a difference value between the first output signal and the second output signal to generate an amplifying output signal, wherein the amplifying output signal correlates with the small signal component;
• wherein the second pixel circuit comprises;
• a contact layer, coupled to a first driving circuit to receive a first drive signal, the contact layer receiving a contact of the finger;
• a first shield layer, disposed below the contact layer;
• a first metal layer, disposed below the first shield layer, and coupled to a second driving circuit to receive a second drive signal;
• and
• a second metal layer, disposed below the first metal layer;
• wherein the first shield layer and the second metal layer are coupled to the second driving circuit to receive a third drive signal;
• and
• wherein the first metal layer is coupled to the second sensing circuit.