Drive circuit of organic light emitting display and offset voltage adjustment unit thereof

A drive circuit, adapted for driving an organic light emitting display (OLED), the driving circuit comprising:

• a digital-to-analog conversion unit;
• a control unit, coupled to the digital-to-analog conversion unit;
• and
• an output unit having a plurality of buffer units, each of the buffer unit comprising:
• an operational amplifier having a differential input stage, a bias stage, an output stage, and an offset voltage adjustment unit, wherein the offset voltage adjustment unit comprises a resistor string and a plurality of latch units coupled to the resistor string, the offset voltage adjustment unit being coupled between the bias stage and a ground, the offset voltage adjustment unit is configured for adjusting a bias current generated by the bias stage;
• and
• a calibration unit, coupled to the latching units and an output terminal of the operational amplifier, the calibration unit operatively controlling operations of the latch units to adjust the bias current of the bias stage according to an output voltage of the operational amplifier;
• wherein, the control unit inserts a calibration period in a driving cycle, during which the control unit enables the calibration unit to perform a calibration procedure, and the calibration unit operatively causes the latch units to enter a latch state to calibrate an output offset voltage of the operational amplifier at the completion of the calibration procedure.