寬負載範圍之高速AMLCD源極驅動緩衝器

Abstract

近年來顯示科技產業開始朝向發展嶄新的高畫質主動式矩陣液晶顯示器。而液晶顯示器也廣泛的使用在常見的電子產品中，舉凡是大尺寸的電視或是小面板的攜帶式電子產品。為了達到高畫質顯示，面板需要更高的解析度。而當嶄新高畫質的面板解析度提高的發展前提之下，源極驅動器對於每一條資料線的暫態反應必須更快；也因此源極輸出緩衝器就得提供更高的迴轉率及更小的直流偏移電壓。 有鑑於此，我們發展出一個使用於液晶顯示器中的高迴轉率並具有頻率補償的源極驅動輸出緩衝器，我們採用0.35-μm CMOS製程，使用5-V的電壓而輸出緩衝器只需消耗5-μA的靜態電流。此外，為了達到高畫質的顯示效果，輸出緩衝器我們設計在當輸出負載為10kΩ/300pF時，迴轉率要小於1-μs；而在當輸出負載為0kΩ/50pF時，我們所設計具有頻率補償的緩衝器也可以有超過30°的相位邊限。因此，我們所設計的源極驅動輸出緩衝器可應用於不同大小尺寸的液晶顯示器。

In recent years, the trend of display goes toward high-definition (HD) display for the active-matrix liquid crystal display (AMLCD). The LCDs haves been used in wide varieties of electronic devices, from large-size TV to small-size portable gadgets. To attain high image quality, high LCD resolution is required. As the HD LCD resolution is increased, the source driver of every column line needs to have fast transient response. Therefore, the output buffer of source driver needs to provide the high slew-rate and low dc offset voltage. A high slew-rate source output driver with frequency compensation was fabricated with TSMC 0.35-μm 2P4M CMOS technology. With 5-V supply voltage, it draws only 5-μA static current. In order to meet the high-performance display quality, the slew-rate of the output buffer should be faster than 1μs under the load of 10kΩ/300pF. However, the phase margin of the circuit needs to be larger than 30° under the load of 0kΩ/50pF. Hence, the output buffer is suitable for both small LCD panels and large size LCD panels.