應用於短距離光纖通訊之無被動電感的面射型雷射驅動電路

An Inductor-less VCSEL Driver for Short Distance Optical Interconnection

彭新展(Hsin-Chan Peng)

指導教授 ： 徐永珍

國立清華大學/電機資訊學院/電子工程研究所/碩士(2013年)

摘要

由於科技的快速發展，尤其是各種可攜式產品的普及化，大眾對於短距離資料傳輸量的需求快速成長，而傳統電傳輸品質以及頻寬受限於銅纜的物理特性在未來幾年會達到其應用的極限，光纖通訊提供高頻寬介面性質而沒有電訊號傳輸介面的許多缺點，故短距離光纖通訊系統是近年來一項重要的研究議題。
短距離光纖通訊系統由於所需能量小，幾乎都是選用面射型雷射二極體來當作電轉光的媒介，而面射型雷射二極體驅動電路(VCSEL Driver)的前置放大器(Pre-Amplifier)通常是以被動電感將操作頻寬提升上去，優點是設計簡單，但被動電感在佈局(layout)中所占的面積非常大，而且由於電感的繞線在電流通過後容易形成電磁場，在元件位置擺放時，必須使電感彼此遠離，又會占去許多面積，所以此篇論文採用主動電感的方式來大幅減小晶片面積。在所設計的電路中使用了負電容、折疊式主動電感、串疊結構、主動回授電路等拓增頻寬技巧降低了功率消耗。此面射型雷射二極體驅動電路採用了TSMC 0.18μm CMOS製程，同時輸出調變電流範圍設計在5mA到15mA。晶片量測的結果上，前置放大器的功率消耗只需182mW，電路佈局面積則是0.48mm×0.44mm，光訊號量測Bit Rate可到7.5Gb/s。

關鍵字

垂直共振腔面射型雷射 ； 前置放大器 ； 負電容 ； 折疊式主動電感 ； 主動回授電路

並列摘要

Due to the wide spread of mobile devices, the needs of short–distance information processing grow fast recently. Since the properties and the bandwidth of electrical communication are restricted by the physical characteristics of copper cables, the application of electrical communication will reach its limit in the near future. However, the optical fiber communication performs well at the high bandwidth interface and has only a few drawbacks at the electrical interface, therefore the short-distance optical fiber communication system has become an important research topic.
Because of low energy consumption of short-distance optical fiber communication system, VCSEL is usually chosen as a trigger for transferring electrical energy to light. The operation bandwidth of Pre-Amplifier in VCSEL driver is usually increased by the inductor due to its simple design. However, the inductor occupies a huge portion of layout, and the coils inside easily generates electromagnetic fields while the current flowing through them. To overcome this issue, the distance between different passive inductor should be extended, which occupies more area in layout. In this thesis, active inductor is introduced to solve the problem above. This design contains negative capacitance, folded active inductor, cascode structure, and active feedback circuit etc. to increase the bandwidth but lower the power consumption. VCSEL Driver is produced by TSMC 0.18μm CMOS fabrication, and the range of current is from 5mA to 15mA. The optical measurement result shows that the power consumption of Pre-Amplifier is only 182mW, the total area of circuit is 0.48mm x 0.44mm, and Bit Rate is 7.5Gb/s.

參考文獻

[6] 劉秉澄，應用於10Gb/s之高效能矽鍺限幅放大器設計，碩士論文，清華大學，新竹，2007。

[2] R. Tao, M. Berroth, and Z. G. Wang, “Low power 10Gb/s VCSEL driver for optical interconnect,” Electronics Letters, vol. 39, no. 24, pp.1743-1744, Nov. 2003.

[3] B. Razavi, Design of Integrated Circuits for Optical Communication Systems. America: McGraw-Hill, 2003.

[5] M. O'Farrell, “Laser driver design in 0.18μm CMOS technology,” master's thesis, Queen's University, Canada, 2010.

[7] 廖偉傑，標準製程下應用於整合型光通訊接收器之光偵測器元件與訊號放大電路設計，碩士論文，清華大學，新竹，2012。