Common voltage generator, display device including the same, and method thereof

A common voltage generator comprising:

• an operational amplifier configured to amplify a difference between a first voltage received at a first input terminal and a second voltage received at a second input terminal and configured to output the amplified voltage as a common voltage to an output terminal;
• a voltage divider connected between the output terminal and a first node, configured to divide a voltage between the output terminal and the first node and configured to output the divided voltage as the first voltage to the first input terminal;
• and
• an input voltage generation unit configured to select and transmit one of a plurality of voltage levels in response to a first output control signal as the second voltage in a first voltage output mode and configured to select and transmit another of the plurality of voltage levels in response to a second output control signal as the second voltage in a second voltage output mode.