Ultrasonic fingerprint identification component, fingerprint identification device and fingerprint identification driving method

An ultrasonic fingerprint identification component, comprising an ultrasonic fingerprint identification circuit and a current supply circuit, the ultrasonic fingerprint identification circuit includes a detection circuit and a source follower circuit, an output terminal of the detection circuit and an input terminal of the source follower circuit are coupled to a sampling node, and an output terminal of the source follower circuit is coupled to the current supply circuit through a signal reading line;

• the current supply circuit is configured to provide a constant current to the output terminal of the source follower circuit during an operation of the ultrasonic fingerprint identification circuit;
• the detection circuit is coupled to a receiving electrode of an ultrasonic sensor and is configured to output a sensing voltage to the sampling node according to an electric signal output by the receiving electrode of the ultrasonic sensor;
• the source follower circuit is configured to output a corresponding source follower voltage to the signal reading line according to the sensing voltage under control of the constant current,
• wherein the current supply circuit comprises:
• a reset circuit, a writing and compensation circuit, an output control circuit and a driving transistor, a control electrode of the driving transistor, the reset circuit and the writing and compensation circuit are coupled to a control node;
• the reset circuit is coupled to a first power supply terminal and a first control signal line and is configured to write a first voltage provided by the first power supply terminal to the control node in response to control of the first control signal line;
• the writing and compensation circuit is coupled to a second power supply terminal, a second control signal line, a first electrode of the driving transistor, and a second electrode of the driving transistor, is configured to write a second voltage provided by the second power supply terminal to the second electrode of the driving transistor and write a control voltage to the control node in response to control of the second control signal line, the control voltage being equal to a sum of the second voltage and a threshold voltage of the driving transistor;
• the output control circuit is coupled to a third power supply terminal and a third control signal line and is configured to write a third voltage provided by the third power supply terminal to the second electrode of the driving transistor in response to control of the third control signal line;
• the driving transistor is configured to output a driving current to the signal reading line in response to the control voltage and the third voltage to supply the constant current to the output terminal of the source follower circuit.