寬頻低雜訊放大器與Ka-頻段功率放大器設計

Abstract

本論文為寬頻低雜訊放大器與Ka-頻段功率放大器設計。第一個電路是製作於砷化鎵假型高速場效電晶體的寬頻低雜訊放大器，並使用於陣列天文望遠鏡系統；第二個電路是製作於互補式金屬氧化半導體製程的Ka-頻段功率放大器。 首先討論，一個以0.1微米砷化鎵假型高速場效電晶體製程製作並使用電感性回授補償高頻增益技術的寬頻低雜訊放大器，增加增益平坦度。此放大器只使用兩級，即可達到3分貝頻寬為3.6-21.3 GHz，而此頻寬超過130%的比例頻寬，小訊號增益為21.7分貝以及雜訊增益為1.2分貝，靜態功率為160毫瓦，晶片面積為1.5毫米平方。 而後，是說一個以90奈米互補式金屬氧化物半導體製程的Ka-頻段轉阻器雙模多爾蒂功率放大器(Doherty power amplifier)使用自適應偏壓電路增加輔助電路的輸出功率以及效率；另外使用對稱電路結構提升6分貝功率退回時的效率。此電路有兩種操作模式，分別為高效率模式與高線性度模式，並使用高轉組比電流式轉阻器達到更高的功率退回時的效率。操作為高效率模式時，達到小訊號增益為20.4分貝以及3分貝頻寬28.7-41.9 GHz。操作高線性度模式時，達到小訊號增益為24.9分貝以及3分貝頻寬28.7-43.3 GHz。在兩個模式下，飽和輸出功率都大於20.9 dBm 以及30%飽和功率附加效率。最後在高效率模式下，功率退回時功率附加效率比線性功率放大器的功率退回時的效率多出0.7倍。

An ultra-wideband low noise amplifier (LNA) in 0.1-μm GaAs pHEMT process is presented. The proposed LNA is designed with the feedback structure to compensate the high-frequency gain, and improve the gain flatness. With only two stages, the 3-dB bandwidth of the LNA covers from 3.6 to 21.3 GHz and 1-dB bandwidth covers from 4.0 to 16.8 GHz. The measured small signal gain (S21) is 21.7 dB and the measured averaged noise figure is 2 dB with dc power consumption of 160 mW. The chip area is 1.5 mm2. A Ka-band transformer-based dual mode Doherty power Amplifier is fabricated in 90-nm CMOS process. The proposed Doherty amplifier is designed with adaptive bias network to increase the auxiliary path output power and efficiency. The symmetrical structure is used to improve the 6-dB power back-off efficiency. The proposed PA offers two operating modes, high efficiency mode (HEM) and high linearity mode (HLM) respectively. The high turn ratio (N=2) current-type transformer is adopted for the Doherty load modulation. In the high efficiency mode, the measured small signal gain is 20.4 dB with 3-dB bandwidth from 28.7 to 41.9 GHz. In the high linearity mode, the small signal gain is 24.9 dB with 3-dB bandwidth from 28.7 to 43.3 GHz. The proposed PA achieves 20.9-dBm saturated output power with above 30% power added efficiency (PAE) in two modes. In the back-off region, the high-efficiency mode is about 1.7 times PAE more than the Class A efficiency.