應用於第五代通訊系統之互補式金屬氧化物半導體功率放大器效率提升研究

Research on the CMOS Power Amplifier with Enhanced Efficiency for 5G Communication System Applications

黃致家(Zhi-Jia Huang)

指導教授 ： 林坤佑

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2019年)

https://doi.org/10.6342/NTU201804103

摘要

毫米波中有數個頻帶範圍已被授權為第五代通信系統。為了達到Gb/s等級的數據傳輸速度，即便使用毫米波頻段，頻寬依然有限。為了在有限頻寬內達到高數據傳輸速率，調變技術將採用高階調變，因此設計功率放大器上需要改善振幅(AM-AM)及相位(AM-PM)失真等特性。此外，為使用多輸入多輸出(MIMO)技術來提升天線輻射的效率，系統上將有多組發射端及功率放大器，故功率放大器的效率也是重要的設計目標。
本論文將從傳統的Class-A/B/C放大器介紹到諧波控制放大器(Class F/F-1)，最後為連續性諧波控制放大器(Continuous Class F/F-1)。內容會分別討論波形、最大輸出功率、效率及基頻和諧波阻抗。
接下來分別探討差動放大器在差模狀態的穩定度和共模情況下的穩定度。中性化電容技術可改善差模的穩定度，反之共模會使其劣化。因此利用在變壓器的閘極串聯電阻，達到共模穩定度的改善。章節最後舉例一個設計在28 GHz使用中性化電容技術的差動功率放大器發生共模振盪，利用雷射切割切除閘極旁路電容，所以閘極路徑變成串聯一大電阻，讓共模振盪得以解除。
為了得到寬頻的大訊號特性，電路使用連續性class-F架構。連續性class-F諧波調控輸出匹配電路以1:1變壓器和並聯一組串聯共振腔所組成，達到連續性class-F所需的輸出阻抗條件。此外，利用設計驅動級的偏壓使AM-PM與功率級反向，達到AM-PM補償效果。
最後介紹一個雙頻class-F功率放大器，覆蓋28 GHz和38 GHz頻段及擁有高效率。雙頻段class-F諧波調控輸出匹配電路以1:1變壓器、多諧振電路、被動元件和寄生元件所組成。將LC共振腔所需的電感替代成變壓器，使LC共振腔與變壓器結合達到最小的輸出匹配網路面積。

關鍵字

毫米波 ； 第五代通信系統 ； AM-AM ； AM-PM ； 連續性class F/F-1 ； 中性化技術 ； 共模振盪 ； 雙頻段 ； 功率放大器

並列摘要

Several mm-Wave bands have been opened for 5G communication systems to achieve the Gb/s data transmission. Despite using the mm-Wave bands, the spectrum is still a limited resource. Therefore, to achieve high data rate in the limited bandwidth, high order modulation schemes are used, hence the AM-AM and AM-PM distortions need to be improved in the design of PA. Since the MIMO technology is used to enhance the efficiency of antenna radiation, the system would have many transmitters and PAs. Thus, the efficiency of PA is also an important design target.
In this thesis, the traditional class-A/B/C amplifiers, harmonic-controlled amplifiers (Class F/F-1) and continuous-mode harmonic-controlled amplifiers (Continuous Class F/F-1) are introduced. The waveforms, maximum output power, efficiency and the impedance of fundamental and other harmonic frequencies will be discussed.
The stability of differential amplifier is analyzed in differential and common modes, respectively. The stability of differential mode can be improved by the capacitor neutralization technique. However, the common-mode stability could be degraded due to neutralization capacitor. Using the series resistor in center tap of the gate transformer can decrease the common-mode gain and thus the common-mode stability can be improved without degrading the differential-mode performance. Finally, an example of 28 GHz differential power amplifier with capacitor neutralization technique is demonstrated. By using laser to cut the bypass capacitor of gate bias, the low-impedance at the center tap of the gate transformer becomes a high impedance due to the series resistor, the oscillation is thus removed.
In order to get the broadband power performance, the continuous class-F topology is used. The continuous class-F harmonic-tuned output matching network is composed of a 1:1 transformer and a parallel series resonator to achieve the impedance condition of continuous class F. Besides, the gate bias of driver stage is designed for the reverse AM-PM distortion to compensate the of AM-PM distortion of the power stage.
Finally, a dual-band class-F PA covering the 28/38 GHz bands is demonstrated with high efficiency. The dual-band class-F operation is obtained by dual-band class-F harmonic-tuned output matching network, which is composed of a 1:1 transformer, parallel multi-resonance networks, passive component, and parasitic components. The inductor of LC tank can be replaced by transformer to combine LC tank and transformer to minimum the area of output matching network.

並列關鍵字

mm-Wave ； 5G Communication System ； AM-AM ； AM-PM ； Continuous Class F/F-1 ； Neutralization Technique ； Common Mode Oscillation ； Dual Band ； Power Amplifier (PA)

參考文獻

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[2] S. Hu, F. Wang, and H. Wang, “A 28GHz/37GHz/39GHz multiband linear Doherty power amplifier for 5G massive MIMO applications,” in IEEE Int. Solid-State Circuits Conf. Dig., Feb. 2017, pp. 32-34.

[3] M. Vigilante and P. Reynaert, “A 29-to-57GHz AM-PM compensated class-AB power amplifier for 5G phased arrays in 0.9V 28nm bulk CMOS,” in Proc. IEEE Radio Freq. Integr. Circuits Symp. Dig., June 2017, pp. 116-119.

[4] A. Chakrabarti and H. Kirsgnaswamy, “High-power high-efficiency class-E-like stacked mmWave PAs in SOI and bulk CMOS: theory and implementation,” IEEE Tran. Microw. Theory Tech., vol. 62, no. 8, pp. 1686-1704, Aug. 2014.

[5] B. Park, S. Jin, D. Jeong, J. Kim, Y. Cho, K. Moon, and B. Kim, “Highly linear mm-Wave CMOS power amplifier,” IEEE Trans. Microw. Theory Techn., vol. 64, no. 12, pp. 4535-4544, May 2016.