應用於K頻段之變壓器回授式低雜訊放大器

Transformer Feedback LNA for K-Band Applications

魏佑霖(Yu-Lin Wei)

指導教授 ： 徐碩鴻

國立清華大學/電機資訊學院/電子工程研究所/碩士(2008年)

摘要

With the growth of the IT industry, the technologies of communication arouse more and more attention in these years. Recently, the demand for high data rate makes the desired operation frequency of RFICs moving toward higher bands. Among the applications, K-band (18-26.5 GHz) is of great interest, which can be used for short-range and high data-rate wireless communications or anti-collision radars for cars (24 GHz).
In this work, four low noise amplifiers (LNA) were realized based on the transformer feedback configuration for K-Band applications, which include cascode, common source, and current-reused technique in different designs. All circuits used the on-chip transformer as the input matching network for better noise and power matching. All of them were implemented by a standard 0.18-□m CMOS technology. Among them, the cascode design achieved a noise figure of 5.4 dB under a power gain of 16.7 dB at 22.6 GHz. The first common source design achieved a noise figure of 4.5 dB under a power gain of 16.7 dB at 22 GHz. The second common source design used two kinds of transformer feedback topologies. It achieved a noise figure of 5.2 dB under the power gain of 16.7 dB at 21.7 GHz. The power consumptions of them are both about 15 mW. The LNA designed by current-reused technique presented a lowest NF of 4.3 dB under a power consumption of only 7.2 mW at the frequency of 22 GHz.

關鍵字

K頻段 ； 低雜訊放大器 ； 變壓器回授 ； 共電流技巧

並列摘要

隨著資訊科技的發展，近年來人們對於通訊技術的需求愈顯重要。也由於對高速率傳輸的需求增加，使得射頻晶片的操作頻率開始不斷的向更高的頻率移動，在眾多不同的應用之中，K頻段(18~26.5GHz)可以算是相當受到注目的其中之一，因為其能夠在短距離的無線通訊之中提供相當高的傳輸速率與頻寬。除此此外K頻段也可以應用於汽車的防撞雷達(24 GHz)等運用。
本論文運用變壓器回授方式設計四個應用於K頻段之低雜訊放大器，包含疊接架構、共源極架構與共電流技巧等不同的架構，以上架構皆會使用在本論文裡不同放大器之設計中。同時所有電路皆使用實作於晶片上之變壓器來設計其輸入匹配網路已獲得良好的雜訊與功率匹配並且運用標準0.18-□m CMOS製程製作以便與後級的基頻電路作整合。在這些低雜訊放大器之中，使用疊接放大架構設計的低雜訊放大器在22.6 GHz具有5.4 dB的雜訊指數與16.7 dB的增益。第一種共源極放大架構設計則是在22 GHz具有4.5 dB的雜訊指數與16.7 dB的增益，而第二種共源極放大架構設計則是使用了兩種不同的變壓器回授方式來做設計，其在21.7 GHz具有5.2 dB的雜訊指數與16.7 dB的增益，以上兩個共源極設計之功率消耗皆約為15毫瓦。最後使用共電流技巧設計之低雜訊放大器則是在功率消耗只有7.2毫瓦的情況下，在操作頻率為22 GHz時具有最低的雜訊指數4.3 dB。

並列關鍵字

K-band ； low noise amplifier ； transformer feedback ； current-reused technique

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