High-Precision Mixed Modulation DAC for an 8-Bit AMOLED Driver IC

Abstract

This paper proposes an 8-bit grayscale AMOLED driver IC with a mixed modulation DAC. This architecture maintains a digital logic component, high-precision 8-bit compensated gamma correction and an output amplifier buffer with low-complexity configuration for the AMOLED display panel. The proposed driver IC with gamma correction consists of a 6-bit resistor-string DAC and a 2-bit polynomial interpolation current-modulation sub-DAC. The two-stage DAC leads to a more compact die size than conventional 8-bit resistor-string DAC, and the polynomial interpolation method provides higher accuracy gray level voltages than linear methods. The source driver IC of the 240 RGB AMOLED display was implemented in the 0.35 $\mu$ m CMOS process with a die area of 2.95 $\times$ 8.9 mm $^{2}$ , including a digital core area of approximately 7.0 $\times$ 1.0 mm $^{2}$ . The DNL and INL of the proposed mixed modulation DAC are of 0.43 LSB and, 0.4 LSB, respectively.