Calibrating circuit and calibrating method for display panel

A calibrating circuit for a display panel, wherein the display panel comprises a source driver, a gate driver, and a pixel circuit comprising a driving transistor, the calibrating circuit in the source driver comprising:

• a pixel sensor having an input terminal coupled to the pixel circuit through a data line of the display panel, for sensing a terminal voltage of the driving transistor during a sensing period, wherein the terminal voltage of the driving transistor is a threshold voltage;
• at least one calibration sensor having input terminals coupled to a first predetermined voltage and a second predetermined voltage;
• an amplifying circuit having an input terminal coupled to the pixel sensor and the at least one calibration sensor, for amplifying the terminal voltage of the driving transistor according to a gain of the amplifying circuit during the sensing period to obtain an amplified terminal voltage, and amplifying the first predetermined voltage and the second predetermined voltage according to the gain of the amplifying circuit during a calibration period to obtain an amplified first predetermined voltage and an amplified second predetermined voltage respectively;
• an analog to digital converter having an input terminal coupled to an output terminal of the amplifying circuit, for converting the amplified terminal voltage into a digital code during the sensing period, and converting the amplified first predetermined voltage into a first digital code and converting the amplified second predetermined voltage into a second digital code during the calibration period;
• and
• a gain adjusting circuit coupled to an output terminal of the analog to digital converter and the amplifying circuit, for adjusting the gain of the amplifying circuit according to the first digital code and the second digital code.