A fingerprint sensor is provided. The fingerprint sensor includes a sensing array sensing fingerprint information of a user, an insulating surface disposed on the sensing array, and a printed circuit board (PCB) disposed under the sensing array. The PCB includes a substrate, a ground plane disposed on the second surface of the substrate, and an electrostatic discharge (ESD) ring disposed on the first surface of the substrate and surrounding the sensing array. The substrate includes a first surface and a second surface opposite the first surface. The ESD ring surrounds the sensing array. When an ESD event occurs, ESD energy is discharged from the ESD ring to the ground plane through a plurality of vias in the substrate without passing the sensing array.