Design of column driver ICs for active-matrix flat panel displays

Abstract

This thesis focuses on the high speed current-mode driving schemes for active-matrix OLED displays and design considerations of low-power area-efficient channel buffer amplifiers for active-matrix LCDs. In Chapter 1, transient charge feedforward driver (TCFD) for high-speed current-mode data driving in AMOLED displays is presented. In order to provide charging current for the parasitic capacitance of a data (column) line, TCFD adaptively generates the required charging current by taking advantage of the parasitic capacitance of an adjacent data line. The TCFD can dramatically enhance the data driving speed by driving a data line 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 \mus driving speed was achieved for 20 nA of data current. The driving speeds were almost constant for data line conditions up to 6 kohm and 40 pF. The TCFD was fabricated in a standard 3.3 V 0.35 $\mu m$ CMOS process and the performance of the TCFD was evaluated by on-chip panel emulation. In Chapter 2, the performance criteria and corresponding design specifications for channel buffer amplifiers in state-of-the-art column driver ICs of active-matrix LCD (AMLCD) applications are presented. In addition, several display patterns and their driving waveforms that enable the prediction of the performance of channel buffer amplifiers in real panel applications are presented. Low-power area-efficient complementary push-pull buffer amplifiers are shown according to the design specifications. By adding an inverting amplifier controlled source follower and dynamic bias control of the inverting amplifier to a conventional two-stage operational amplifier, the operation voltage range was extended, as well ...