Transient Charge Feedforward Driver for High-Speed Current-Mode Data Driving in Active-Matrix OLED Displays

Abstract

A transient charge feedforward driver (TCFD) is presented for high-speed current-mode data driving in active-matrix organic LED (AMOLED) displays. In order to provide charging current for the parasitic capacitance of a column line (CL), TCFD adaptively generates the required charging current by taking advantage of the parasitic capacitance of another adjacent CL. The TCFD can dramatically enhance the data driving speed by driving a CL with the summing current of data and the required charging current. The adaptive generation of the required charging current and the summing operation are realized by the simultaneous operation of negative-and positive-feedback loops. The loop transfer function is revealed and the stability conditions are discussed. By applying the TCFD, a 7 mu s driving speed is achieved for 20 nA of data current. The driving speeds are almost constant for CL conditions up to 6 k Omega and 40 pF. The TCFD is fabricated in a standard 0.35-mu m CMOS process and the performance of the TCFD is evaluated by on-chip panel emulation.