A 12‐bit segmented resistor‐capacitor digital‐to‐analog converter for a display driver IC of a large TFT‐LCD panel system

Abstract— A 12‐bit segmented R‐C DAC to support a linear gamma curve has been proposed and fabricated in a 720‐channel LCD source driver with a 16‐V 1‐poly 3‐metal high‐voltage CMOS process. The proposed DAC has a global resistor string and sample‐and‐hold buffers. A MSB voltage selected by the upper 6 bits of input data and a LSB voltage selected by the lower 6 bits of input data are summed by using a sample‐and‐hold operation with offset cancellation in the proposed DAC. The measured DNL was less than 0.3 LSB, and the output voltage deviation was less than 3 mV in all gray levels. Although two sample‐and‐hold buffers were adopted to operate alternatively, the die size was as small as 24.9 mm², which was only an 8.3% increase compared to that of a conventional 8‐bit 720‐channel source driver. Because of its good performance with small area, the proposed DAC can be a good low‐cost solution for a 10‐bit TV system.