A 10-bit LCD column driver with piecewise linear digital-to-analog converters

A 10-bit LCD column driver, consisting of piecewise linear digital to analog converters (DACs), is proposed. Piecewise linear compensation is utilized to reduce the die area and to increase the effective color depth. The data conversion is carried out by a resistor string type DAC (R-DAC) and a charge sharing DAC, which are used for the most significant bit and least significant bit data conversions, respectively. Gamma correction voltages are applied to the R-DAC to fit the inverse of the liquid crystal transmittance-voltage characteristic. The gamma correction can also be digitally fine-tuned in the timing controller or column drivers. A prototype 10-bit LCD column driver implemented in a 0.35-mu m CMOS technology demonstrates that the settling time is within 3 mu s and the average die size per channel is 0.063 mm(2), smaller than those of column drivers based exclusively on R-DACs.