Patent ID: 8633881

Claim:
A display driving circuit for use with a liquid display panel, the display driving circuit comprising: a system interface to which display data is inputted from an external; a memory in which the display data is stored; a grayscale voltage generation circuit which generates a plurality of grayscale voltages; a gamma adjustment circuit which adjusts a gamma characteristic; and a circuit which provides to the liquid display panel, the grayscale voltages according to the display data from the memory, wherein the grayscale voltage generation circuit includes: a first resistor ladder including a first variable resistor, a first resistive voltage dividing circuit, a second variable resistor, a plurality of second resistive voltage dividing circuits, a third variable resistor, a third resistive voltage dividing circuit and a fourth variable resistor, which are coupled in series between a first voltage and a second voltage different from the first voltage; a first selector which selects a predetermined voltage by selecting one of a plurality of output lines of the first resistive voltage dividing circuit; second selectors which select predetermined voltages by selecting one of a plurality of output lines of each of the second resistive voltage dividing circuits; a third selector which selects a predetermined voltage by selecting one of a plurality of output lines of the third resistive voltage dividing circuit; and a second resistor ladder coupled to receive outputs of the first to the third selectors at predetermined portions thereof, and including a plurality of resistors coupled between a third voltage according to a voltage at a connection node between the first variable resistor and the first resistive voltage dividing circuit and a fourth voltage according to a voltage at a connection node between the third resistive voltage dividing circuit and the fourth variable resistor, wherein the second resistor ladder provides the plurality of grayscale voltages by dividing a voltage between the third voltage and the fourth voltage, wherein the gamma adjustment circuit includes: an amplitude adjustment register which adjusts an amplitude of the gamma characteristic and which sets a first value to control the first resistor and the fourth variable resistor; a gradient adjustment register which adjusts an gradient of intermediate portion of the gamma characteristic and which sets a second value to control the second resistor and the third variable resistor; a micro adjustment register which adjusts an amplitude of the gamma characteristic and which sets a third value to control each voltage selected from the first selector, the second selectors and the third selectors.