微波低功耗低雜訊放大器與毫米波多爾蒂功率放大器的設計

Abstract

本論文包含兩部分。第一部分是一個針對下個世代的無線電天文接收機之需求所設計的C波段(C-band)極低功耗(ultra-low-power)低雜訊放大器。第二部分是一個支持高頻段第五代無線通訊系統的Ka波段(Ka-band)多爾蒂功率放大器(Doherty power amplifier)。 第一部分的論文呈現了一個使用90奈米金氧半場效電晶體製程設計的C-band極低功耗低雜訊放大器，這個寬頻低雜訊放大器支持ALMA頻段中4-6 GHz的頻段。為了因應嚴格的功率限制，我們提出了一個合適的偏壓選擇方法，同時，我們利用串級的共源極放大器和四個元件組成的阻抗匹配網路來增加放大器頻寬。此放大器在消耗963微瓦之下，在42.4%的分頻寬比內提供平均17.5 dB的小訊號增益以及平均3.1 dB的雜訊指數，在目前已發表的S波段(S-band)以及C波段低功耗低雜訊放大器中具有競爭力。 第二部分的論文展示了一個使用0.1微米砷化鎵假型高速場效電晶體(pHEMT)製程設計的Ka波段多爾蒂(Doherty)功率放大器。為了支持第五代無線通訊系統，這個功率放大器的操作頻率鎖定在37-40 GHz來提供較佳的頻寬和位元速率。我們採用對稱的多爾蒂放大器架構以及二級共源極放大器來維持良好的增益和功率退回時的效率，再者，我們也利用電感與電容共振的方法以及分佈式阻抗轉換器來縮小功率結合網絡所佔據的晶片面積。量測結果顯示此放大器在39 GHz到41 GHz寬中，除了提供23 dBm的飽和輸出功率(Psat)和27-29%的峰值功率附加效率(PAE) ，也在6 dB功率退回處提供20-21%的功率附加效率。在目前已發表的Ka波段砷化鎵多爾蒂功率放大器中，這個作品在40 GHz左右提供最好的6-dB功率退回功率附加效率。

This thesis consists of two parts. The first part presents a C-band ultra-low-power low noise amplifier for next-generation radio astronomical receivers. The other describes a Ka-band Doherty PA supporting the upper-frequency band of fifth-generation wireless systems. The first part of the thesis presents a C-band ultra-low-power LNA fabricated in TSMC 90-nm CMOS technology. This wideband LNA is targeted on 4-6 GHz, which is a part of IF band in ALMA bands. Due to restricted dc power consumption, a methodology of selecting a proper bias is proposed. Meanwhile, cascaded common-source amplifiers and four-element L-matching network enhance the bandwidth of this work. While consuming only 963 μW, this work demonstrates a 42.6% fractional bandwidth with an average gain of 17.5 dB and an average noise figure of 3.1 dB. To the author’s knowledge, this LNA shows competitiveness among published S-band and C-band low-power LNAs. The other part of the thesis demonstrates a Ka-band Doherty PA fabricated in WIN’s 0.1-μm D-mode GaAs pHEMT process. Supporting 5G wireless systems, the operating frequencies of this work is targeted at 37-40 GHz to provide broader bandwidth and higher data rate. To achieve good gain and backed-off efficiency, a symmetric Doherty configuration and two-stage cell amplifiers are chosen in the design. Moreover, the LC-resonance method and distributed impedance transformer help to reduce the area of the power-combining network. The measured results of this work show a peak PAE of 27-29% and 6-dB backed-off PAE of 20-21% from 39 to 41 GHz while providing a Psat of 23 dBm. To the author’s knowledge, this work exhibits the best 6-dB backed-off efficiency at frequencies around 40 GHz among published Ka-band GaAs Doherty PA.