CAPACITIVE FINGERPRINT SENSING CIRCUIT AND SENSOR

摘要

The present invention relates to the field of fingerprint recognition. Provided are a capacitive fingerprint sensing circuit and sensor. The sensing circuit comprises a counteracting module and a feedback amplifier; a first input end of the counteracting module is connected to a first external drive source; a second input end of the counteracting module is connected to a second external drive source by a finger pressed on the second input end; the output end of the counteracting module is connected to the input end of the feedback amplifier; signals outputted by the first external drive source and the second external drive source are in phases opposite to each other; signals of the first external drive source being connected to the counteracting module and signals of the second external drive source being coupled to the counteracting module are counteracted to obtain fingerprint sensing signals related to the fingerprint depth; the output end of the feedback amplifier outputs amplified fingerprint sensing signals. The capacitive fingerprint sensing circuit and the sensor provided in the embodiment of the present invention use the external drive source and the counteracting module in opposite phases to attenuate the portion irrelevant to the fingerprint, and only amplify differential mode signals, thus improving fingerprint sensitivity.