A Compact and Power Efficient 10-Bit Source-Driver IC With Low-Voltage Gamma Slope DAC for Mobile OLED Displays

This article presents a compact and power efficient 10-bit source driver IC (SD-IC) for mobile organic light emitting diodes (OLEDs) displays, with a proposed low-voltage (LV) gamma slope digital-to-analog converter (DAC), MSB-dependent segment restorer (MDSR), and data/phase-dependent current modulation (DPCM). Conventional SD-IC uses a high-voltage (HV) resistor DAC (RDAC), which occupies a large silicon area. The LV gamma slope DAC utilizes LV MOSFETs and a slope-based structure, significantly reducing the overall DAC channel silicon area compared to conventional HV RDACs. By adopting MDSR, the LV DAC output is restored to the original gamma voltage without requiring multiplication. Additionally, DPCM digitally controls the tail current based on input data and operation phases, allowing the buffer amplifier to reduce the static current of each channel. The proposed 10-bit SD-IC was fabricated using a 65-nm CMOS process. The circuit area of the proposed 10-bit SD-IC is 2411 μm², achieving an area reduction of 65.5% and 89.7% compared to conventional 8-bit and 10-bit SD-IC using HV RDAC. Measurement results show that the maximum differential nonlinearity (DNL) and integral nonlinearity (INL) are + 0.49 LSB and + 0.85 LSB, respectively, with an LSB voltage of 4.3 mV. The measured maximum deviation of voltage outputs (DVOs) among 40 channels is 10 mV.