Patent ID: 7400312

Claim:
A common voltage adjustment circuit for a liquid crystal display panel comprising a plurality of display units, each coupled to a common electrode, the common voltage adjustment circuit comprising: a first register storing a plurality of digital DC voltage values and outputting a corresponding digital DC voltage value according to a first indication signal; a second register storing a plurality of digital AC voltage values and outputting a corresponding digital AC voltage value according to a second indication signal; a first digital-to-analog converter coupled to the first register and converting the received digital DC voltage value to a first value; a second digital-to-analog converter coupled to the second register and converting the received digital AC voltage value to a second value; and a regulator coupled to the first and the second digital-to-analog converters, adjusting a first and a second voltage signals according to the first and the second values respectively, and outputting the adjusted first and the adjusted second voltage signals to provide a common voltage to the common electrode; wherein the first voltage signal is a DC voltage signal with a voltage value varied in accordance with the first value, and the second voltage signal is an AC voltage signal with an amplitude varied in accordance with the second value.