CAPACITIVE FINGERPRINT SENSOR

摘要

The present invention relates to a capacitive fingerprint sensor. The capacitive fingerprint sensor may firstly sense a difference in capacitance and amplify a signal corresponding to the sensed difference value and then secondly amplify the amplified signal again in a pixel to improve sensing sensitivity. Thus, an upper protection film of the sensor may be increased in thickness due to the improvement of the sensing sensitivity, to thereby have a strong tolerance of electrostatic discharge (ESD) and physical shocks. The capacitive fingerprint sensor includes: a fingerprint sensing electrode Cfp for sensing a fingerprint of the human body; a first transistor T1 in which an amount of current flowing therethrough is changed according to an output voltage of the fingerprint sensing electrode; a second transistor T2 in which an amount of current flowing therethrough is changed according to a difference in current flowing through the first transistor T1; and a third transistor T3 by which a gate electrode of the first transistor T1 is reset, and the gate electrode of the first transistor T1 is capacitively coupled through a pulse signal.