切換電容技術在液晶顯示器省能研究上之應用

The Saving-Power Research of TFT-LCD with Switched-Capacitor Technique

陳鴻立(Hung-Li Chen)

指導教授 ： 宋國明

國立臺北科技大學/電資學院/電機工程系所/碩士(2008年)

摘要

本論文旨在利用切換電容技術來設計並製作液晶顯示面板用之數位類比轉換器，該數位類比轉換器的功能係可將數位視訊信號轉換為驅動面板用之類比訊號，藉以控制透光量。由於該數位類比轉換器係搭配子畫素(sub-pixel)使用，故其使用量相當大，因此若能成功地使該數位類比轉換器達到省能效果，相信對於低耗能液晶顯示面板的開發有著極大的意義，可大大提高液晶顯示面板的產業競爭力。
緣此，本論文在省能研究的規劃，分數位類比轉換器電路跟參考電壓源二個方向去實現省能研究；第一個方向是在數位類比轉換器輸出端接上切換電容式取樣與保持電路，延長畫素顯示時間，避免產生失真現象。並且利用電容與切換開關來取代分壓電阻，應用在液晶顯示器上，並且對分壓電阻的數位類比轉換器與切換電容式的數位類比轉換器電路做耗能比較，從比較結果去了解節省耗能的可行性，進而達到省能的效果；第二個方向是電源供應的控制器研發，即利用來自閂鎖(Latch)的數位訊號，經由該數位訊號偵測器與數位時脈控制電路來共同控制電力的供應，達到「有需要時才供應電力」的省電效果。

關鍵字

數位類比轉換器 ； 切換電容式 ； 取樣與保持電路 ； 電源供應控制器

並列摘要

This thesis presents the design and application of the digital-to-analog converter with switched-capacitor technique for Thin-Film Transistor (TFT) panels. The goal is to save the power consumption. In general, the digital-to-analog converter is used to transform digital signal to analog signal for driving Thin-Film Transistor (TFT) panel and to control the data transmittance. So that every sub-pixel in TFT works with a digital-to-analog converter. That is , there are many digital-to-analog converters in TFT-LCD. If the digital-to-analog converter could save the power consumption, we know that the low power consumption TFT-LCD is coming and will be popular in the future.
In this thesis, we focus on the design of digital-to-analog converter and voltage reference for the purpose of saving power in this thesis. About digital-to-analog converter design, the sample and hold circuit is used to connect to the output of DAC for keeping the display time of sub-pixel and to avoid from distortion. Furthermore, the switched-capacitor technique is used to the resistor in DAC which includes in the TFT-LCD. According to the simulated results, we need to point out which is the winner. Beside, the designer pays attention to control the power supply, which is considered to work with 「work on demand」 concept. That is, we use the latch signal sensing circuit and the controlled circuit to control the power supply. If the TFT-LCD works, so is the power supply. Otherwise the power supply will be shut down to save power consumption.

並列關鍵字

Digital-to-analog converter ； switched-capacitor ； sample and hold ； Power controller

參考文獻

[3] D. A. Johns and K. Martin, Analog Integrated Circuit Design, John Wiley & Sons, Inc., 1997.

[6] R. Jacob Baker, Harry W. Li, and David E. Boyce, CMOS circuit design, layout, and simulation, IEEE, Inc., 1997.

[7] L. E. Jr. Boylston, K. Brown, and R. Geiger, “Enhancing performance in interpolating resistor string DACs”, IEEE 2002 45th Midwest Symposium on Circuits and System Vol. 2, Aug. 2002, pp. II-541-II-544.

[8] Un-Ku Moon, J. Silva, J. Steensgaard, and G. C. Temes, “A switched-capacitor DAC with analog mismatch correction”, The 2000 IEEE International Symposium on Circuits and Systems, May 2000, pp. 421-424.

[9] Shu-Yuan Chin and Chung-Yu Wu, “A 10-b 125-MHz CMOS digital-to-analog converter (DAC) with threshold-voltage compensated current sources”, IEEE Journal of Solid-State Circuits, Nov. 1994, pp. 1374-1380.