Tft-based fingerprint sensing system with corrected read-out

A fingerprint sensing system for sensing a finger surface of a finger, comprising:

• a plurality of conductive selection lines arranged in parallel to each other;
• a plurality of conductive read-out lines arranged in parallel to each other and crossing the selection lines;
• selection circuitry coupled to each selection line in the plurality of selection lines, and controllable to provide a selection signal on at least one selected selection line in the plurality of selection lines;
• a plurality of pixel elements, each being formed at a respective intersection between a selection line in the plurality of selection lines and a read-out line in the plurality of read-out lines, each pixel element in the plurality of pixel elements comprising:
• a sensing element responsive to a property indicative of a distance between the sensing element and the finger surface to provide an output indicating a sensed value of the property;
• and
• a sensing signal providing element coupled to the sensing element, the selection line and the read-out line, the sensing signal providing element being configured to provide to the read-out line, in response to the selection signal being provided on the selection line, a sensing signal being dependent on the output provided by the sensing element;
• a reference signal source configured to provide a reference signal;
• and
• read-out circuitry coupled to each read-out line in the plurality of read-out lines and to the reference signal source, the read-out circuitry being configured to:
• acquire a read-out signal via a read-out line connected to a selected pixel element, when the selected pixel element provides the sensing signal;
• acquire the reference signal from the reference signal source;
• form a corrected read-out signal for the selected pixel element based on the read-out signal and the reference signal;
• and
• provide corrected read-out signals for each pixel element in the plurality of pixel elements, wherein the fingerprint sensing system comprises:
• a TFT module including at least the selection lines, the read-out lines, and the pixel elements;
• and
• an ASIC coupled to the TFT-module, the ASIC including at least a portion of the read-out circuitry.