以比較器為基礎的低功率小面積的行驅動器緩衝器

Abstract

液晶顯示器是目前最廣泛被使用的顯示技術。比起傳統的陰極射線管技術，液晶顯示器讓顯示螢幕做的更輕薄。液晶顯示器的顯示原理是擋住背光源的光而不是自己本身發亮，因此比起其他顯示技術更為省功率消耗。 隨著顯示器朝向低功率、輕薄、高品質不斷進步，首要解決的就是發展出低功率、高速、高解析度的液晶顯示器驅動器。液晶顯示器驅動器一般包含基極驅動器、行驅動器、參考電壓源和一些邏輯電路。其中行驅動器是最重要的，因為此部分電路需要推動較大的輸出負載。在行驅動器之中，輸出緩衝器消耗最多的功率，驅動速度、解析度也和緩衝器相關。一般的行驅動器緩衝器是由放大器所組成，但也因此消耗較多的功率。 在這篇論文中，我們提出了一個以比較器為基本架構的低功率小面積的行驅動器緩衝器。此架構是在傳統的行驅動器緩衝器上加上一個比較器和充電幫浦。充電幫浦經由比較器判斷輸入信號的狀態而打開，而在穩定狀態時關掉。此電路的充電時間是決定於充電幫浦而非傳統的放大器。電路實作上使用標準0.35微米互補金氧半導體製程，所設計的類比緩衝器可以成功地在1.1微秒之內對輸出頻道充放電；在5伏電壓源供應下，靜態電流消耗為1.1微安培。此電路的晶片面積為0.98 × 0.60 毫米平方。

LCD (liquid crystal display) is becoming the most popular technology used for displays in these days. LCD makes displays to be much thinner than traditional cathode ray tube (CRT) technology. Since LCD works on the principle of blocking light rather than emitting it, the power consumption is much less than LED and gas-display displays. With the evolution of low-power, light-weight, and high-quality displays, the critical demand is to evolve a low-power consumption, high-speed, and high-resolution LCD driver. A LCD driver generally consists of a gate driver, a column driver, reference voltages, and control logic circuits. The column driver is the crucial part for low-power, high-speed, and high-resolution due to its large output loading. Among circuits consisting in a column driver, output buffers consume the most power and determine the speed and resolution. Some LCD column driver buffers were proposed. However, they were almost op amps, which is the reason for high power consumption. In this thesis, a comparator-based ultra low-power area-efficient column driver buffer is proposed. The proposed approach adds a comparator and a charge pump in the traditional column driver buffer structure. The comparator senses the transients of the input to turn on the charge pump, which is off in the steady state. The slew rate of the circuit is determined by the charge pump but not the op amp. Fabricated in a standard 0.35-μm CMOS technology, the analog buffer can successfully charge or discharge channels in less than 1.1 μs while dissipating 1.1 μA static current form a 5-V power supply. The die size is 0.98 × 0.60 mm2.