寬頻氮化鎵功率放大器及應用於多進多出雷達系統之雙模態CMOS功率放大器之研究

Abstract

此論文分為三個主要部分，探討在2-6 GHz頻段及6-18 GHz頻段之GaN寬頻功率放大器，以及應用於MIMO雷達系統之可切換雙模態功率放大器。 第一部分介紹之2-6 GHz頻段寬頻放大器設計使用0.25微米氮化鎵高電子遷移率電晶體製程。該電路使用磁耦合共振腔作為輸出匹配網路及電容性和電感性磁耦合共振腔實現寬頻級間匹配。量測結果顯示，其全頻段飽和輸出功率為36.3至40.9 dBm，功率附加效率為8.8至44.4%，以及其小訊號增益為16.9至23.2 dB。並且由於高瓦數的輸出功率，熱能的產生也不可忽視，因此另外設計了銅塊以加速散熱，使其能夠達到更好的量測結果。 第二個部分為6-18 GHz頻段寬頻放大器，同樣使用0.25微米氮化鎵高電子遷移率電晶體製程。相較於第一部分，雖然比例頻寬相等，但是由於較為高頻，因此絕對頻寬較大，在比較了磁耦合共振腔、電容性及電感性之磁耦合共振腔以及多階電抗性匹配後，採用多階電抗性匹配網路以達到寬頻匹配效果。同第一部分，由於其高瓦數之輸出功率，故也加入了銅塊設計以加速散熱。量測結果顯示，其全頻段飽和輸出功率為37.2至42.5 dBm，功率附加效率為10至33.3%，以及其小訊號增益為7.9至17.7 dB。 第三部分則是MIMO雷達系統之雙模態功率放大器之設計。此雙模態功率放大器可隨使用需求，切換雷達系統中常用的TDM或者BPM模態。透過在輸出端加上三組開關，並控制三組開關的狀態以決定使用模態。此外在驅動級放大器的設計使用交叉對架構，以產生BPM所需要的180度相位差。並且在此架構下，能夠改善傳統架構中，兩種模態EIRP不相等的問題。在TDM模態下，此電路量測飽和功率為16.6 dBm，功率附加效率為15.4%；在BPM模態下，飽和功率為15.8 dBm，功率附加效率為26.4%。兩種模態之小訊號增益皆超過21 dB。

This paper is divided into three main parts, focusing on the design of GaN wideband power amplifiers operating in the 2–6 GHz and 6–18 GHz, as well as a switchable dual-mode PA for MIMO radar systems. The first part presents a 2–6 GHz wideband power amplifier implemented using a 0.25-μm GaN HEMT process. Magnetically coupled resonators are utilized as the output matching network, while capacitively and inductively coupled resonators are used for inter-stage matching to achieve the desired broadband effect. Measurement results show that the amplifier achieves a saturated output power ranging from 36.3 to 40.9 dBm, a power-added efficiency (PAE) between 8.8% and 44.4%, and a small-signal gain from 16.9 to 23.2 dB. Due to the high output power, thermal issues arise, and a copper block is designed to improve heat dissipation and enhance measurement performance. The second part discusses a 6–18 GHz wideband power amplifier which is also fabricated using the 0.25-μm GaN HEMT process. Although the relative bandwidth is similar to the first part, the higher operating frequency leads to a wider absolute bandwidth. After evaluating magnetically coupled resonators, capacitively and inductively coupled resonators, and multi-stage reactive matching networks, this work adopts the multi-stage reactive matching approach to achieve the desired wideband performance. Similarly, a copper block is added to improve heat dissipation. Measurement results demonstrate a saturated output power ranging from 37.2 to 42.5 dBm, a power-added efficiency (PAE) between 10% and 33.3%, and a small-signal gain from 7.9 to 17.7 dB. The third part proposes a dual-mode power amplifier for MIMO radar systems, capable of switching between Time-Division Multiplexing and Binary Phase Modulation modes depending on application needs. Three switches are added at the output terminal, and the PA operating mode is determined by controlling their states. A cross-pair architecture is adopted in the driver stage to generate the 180° phase difference required for BPM mode. This architecture also helps address the EIRP imbalance issue commonly seen in conventional designs. Measurement results show that the PA achieves a saturated output power of 16.6 dBm and 15.8 dBm in TDM and BPM modes respectively, with corresponding PAEs of 15.4% and 26.4%. In both modes, the small-signal gain exceeds 21 dB.