A novel programmable wide swing buffer for OLED source driver

Abstract

This paper presents the design of an output buffer with DAC functionality, which meets the requirements of small size, low power consumption, and high precision for OLED source driver chips. The two-stage DAC has a smaller area compared to traditional resistor string DACs, providing higher precision grayscale voltages that better meet the requirements of display drivers. The buffer utilizes a rail-to-rail input stage and Class AB output stage to achieve a wide input-output voltage range. Cascode Miller compensation is employed to improve stability, and a programmable tail current source with current steering DAC is used to realize 3-bit interpolation, saving overall chip area and power consumption. In the HLMC 55 nm CMOS process, the buffer has a rise time of 0.52 us and a fall time of 0.6 us for input voltages ranging from 0-1.2 V. The buffer occupies an area of 35×30 um2.