Data driver IC design for AMOLED displays and AMLCDs

Abstract

This thesis addresses data driver ICs for the two flat panel display technologies of Active Matrix (AM) OLEDs and Active Matrix (AM) LCDs. A compact channel DAC architecture and high speed current-mode output buffers are presented for AMOLED data drivers. And an area-efficient channel DAC structure with excellent channel uniformities is proposed for AMLCD data drivers. In Chapter 1, a compact channel DAC architecture is introduced. An area-efficient 9 bit segmented DAC is fabricated in a standard $0.35 \mu m$ CMOS process. The DAC uses a cascaded-dividing DAC structure for seven least significant bits (LSBs) which leads to a very compact chip implementation suited for channel DACs in AMOLED driver ICs. The implemented chip area of the 9 bit DAC is $65 \times 833 \mu m^2$ and the chip’s power consumption is $37 \mu W$ per DAC. Compared with the previous DAC architectures, the proposed DAC architecture performs excellently in terms of a composite DAC performance which includes chip area, power consumption, and bit-resolution. In Chapter 2, a fast and compact output buffer suitable for small to medium AMOLED displays is presented. An improved transient current feedforward (ITCF) driver is designed for compact implementation and low power consumption by adopting de-multiplexing operation of the proposed driver, based on the fast driving speed of $6 \mu s$ for the panel load of $6k\Omega$ / 40pF which is equivalent to that of XGA AMOLED displays. The driver has structural advantages of simple frequency compensation and low power consumption which come from the elimination of an internal OTA. The chip implementation provides that the area of the driver is $32.5 \times 217 \mu m^2$, and the power consumption $6.5 \mu A$ for each channel. In Chapter 3, a fast current-mode output buffer for full-HD AMOLED displays is addressed. A push-pull transient current feedforward (PP-TCF) driver is designed to have a complete push-pull function and a loop gain control for e...