A Compact High-Performance 10-bit 30-Channel OLED Driver Using Switched Capacitor Circuit for High-Linearity Application

This work proposes a new OLED driver architecture with 10-bit segmented DAC and switched capacitor multiply-by-two circuit application. A 30-channel 10-bit switched capacitor driver chip prototype is implemented in 0.18-μm CMOS technology. In this architecture, the achieved output range is 1.5-4.8V for an input range of 1.5-3.15V, which is suitable for OLED driver with different colors. This architecture is not only converting the digital input signal to analog output for the display panel but also giving amplified high output voltage range. In the segmented DAC, 6-bit coarse DAC and 4-bit fine DAC are used for the input voltage range 1.5-3.15V. In a conventional RDAC for the output voltage of 4.8V, it requires 214 switches i.e., 14-bit RDAC for the same resolution. Hence, conventional RDAC driver is four times larger than the proposed innovative very compact and high speed 10-bit segmented DAC switched capacitor OLED driver. The new architecture drastically reduces the number of switches and complex metal routing which results in reduced power consumption and good settling time. In the proposed OLED driver, no extra buffer is required as switched capacitor op-amp is applied for the same purpose with a gain of more than one. This high-resolution design with small die area also improves the linearity and uniformity with low-power consumption. The post-simulated results show that the OLED driver exhibits the maximum DNL and INL of 0.03 LSB and −0.06 LSB, respectively, with an LSB voltage of 3mV. The one-channel area is 0.586mm × 0.017mm and the settling time is 4.25μs for 30kΩ and 30pF driving load.