本文提出一個低功率消耗的雷射二極體驅動電路，並討論直流耦合（DC coupling）與交流耦合（AC coupling）兩種介面電路來連接驅動電路與雷射二極體。我們使用台灣積體電路（TSMC）0.35mm的CMOS（complementary metal-oxide-semiconductor，互補式金屬氧化物半導體）製程參數來做模擬，其資料傳輸速率（data rates）是在1.25Gb/s的環境下執行。該驅動電路包含三個主要模組區塊：PECL（positive-referenced emitter-coupled logic）to CMOS邏輯電路、調變電流產生電路（modulation current generation circuit）、以及偏壓電流產生電路（bias current generation circuit）。在討論有關使用直流耦合（DC coupling）介面時，因為Headroom不足的問題而導致無法工作在1.25Gb/s的要求。所以我們加以討論使用交流耦合（AC coupling）介面電路來解決Headroom的問題（“headroom” 指的是單個線路路徑的總和個別元件的壓降與供應電壓 之間的比較）。

　　　　　In this paper, we present a low-power laser diode driver, using a DC (direct current) or AC (alternating current) coupling interface circuit to connect it with laser diode. The TSMC (Taiwan Semiconductor Manufacturing Company) 0.35mm 1P4M CMOS (complementary metal-oxide-semiconductor) technology parameters are used to simulate the circuit. The data rate of simulation is 1.25Gb/s. The proposed laser driver includes three blocks: PECL (positive-referenced emitter-coupled logic) to CMOS logic circuit, modulation current generation circuit and bias current generation circuit. Using a DC coupling interface circuit will result in the “headroom” problem, so that the data rate 1.25Gb/s cannot be achieved. Therefore, we adopt the AC coupling interface circuit to solve the “Headroom” problem.