TFT-LCD panel driver IC using dynamic function shuffling technique

Most of the power supplied to a thin-film transistor liquid crystal display (TFT-LCD) panel is consumed at the video signal input lines of the driver ICs, and at the panel vertical lines driven by the driver ICs. The signal frequency at the video signal inputs is about 240 MHz/spl divide/ (number of lines) and about 60 kHz at the vertical lines assuming a super extended graphics array (SXGA) display format. The parasitic capacitance of each line is over 60 pF on the video input side and over 150 pF at the vertical lines. The required signal amplitude at the vertical lines, which depends on the liquid crystal material, is always more than 3 V/sub pp/ for good black and white picture contrast. Conversely, a small signal amplitude is crucial to low power consumption and low electromagnetic radiation. Thus, a gain stage is needed to amplify the signals. For reasons of signal processing speed, the sample and hold (SH) stage precedes the gain stage. However, this configuration increases the offset pedestal originating from the SH stage at the gain stage. To overcome this, dynamic function shuffling is introduced in this CMOS driver IC.