An electrically floating capacitor plate defines a sensing capacitor with a fingerprint sensing surface thereabove. A reference voltage pulse is selectively applied to a pixel input node that is capacitively coupled to the floating plate, which in turn is capacitively coupled to the input node of a charge...http://www.google.fr/patents/US6636053?utm_source=gb-gplus-shareBrevet US6636053 - Capacitive pixel for fingerprint sensor
