Display device having improved contrast ratio

A data driver comprising:

• a shift register that includes a plurality of stages connected to each other one after another and that is configured to sequentially output control signals;
• a latch configured to receive image data and to store the image data in a pixel row unit in response to the control signals;
• a digital-to-analog converter configured to receive reference gray-scale voltages including positive reference gray-scale voltages and negative reference gray-scale voltages, and configured to convert the image data output from the latch to gray-scale voltages;
• and
• an output buffer configured to output data voltages buffered from the gray-scale voltages to pixels of a display panel,
• wherein the output buffer comprises a plurality of buffer circuits each including a first amplifier having a first voltage input terminal configured to receive a first voltage, a second voltage input terminal configured to receive a second voltage lower than both the first voltage and a common voltage for the pixels, an input terminal configured to receive a corresponding gray-scale voltage of the gray-scale voltages, and an output terminal configured to output a corresponding data voltage of the data voltages to a corresponding pixel of the pixels.