High-efficiency GaN HEMT Power Research Articles

Design of High-Power High-Efficiency Broadband GaN HEMT Power Amplifier for S Band Applications using Load-Pull Technique

This work reveals the design for broadband high-power high-efficiency GaN HEMT power amplifier, operating in the frequency band ranging from 2.15 GHz to 2.65 GHz. The proposed structure is implemented using Cree GaN HEMT CGH40010 transistor. The high-power and high-efficiency performances over the broadband bandwidth are achieved using the load-pull technique. The proposed power amplifier is unconditionally stable over the entire operating frequency band. With the neatly designed matching circuits, the introduced power amplifier shows an excellent input/output matching. The simulated results show a flat power gain of 15 dB with an output 1-dB compression point of 14 dB. In terms of largesignal performance, the proposed amplifier reaches a saturated output power of 41.3 dBm (~13.6 Watts) with a PAE of 64% and a drain efficiency of 72%. The proposed design achieves an excellent linearity with an output third order two-tone intercept point TOI of 48 dBm.

고조파 정합 기법을 이용한 고효율 GaN HEMT 전력 증폭기

본 논문에서는 고조파 정합 기법을 이용하여 고효율 GaN HEMT 전력 증폭기를 설계 및 제작하고, 그 특성을 측정하였다. 고효율 특성을 얻기 위해 고조파 로드풀 시뮬레이션을 활용하였다. 즉, 기본 주파수뿐만 아니라 2차, 3차 등의 고조파에서 최적의 부하 임피던스를 찾아내었다. 이러한 고조파 로드풀 시뮬레이션 결과를 바탕으로 출력 정합 회로를 설계하였다. 제작한 전력 증폭기는 중심 주파수 1.85 GHz에서 선형 전력 이득 20 dB 및 33.7 dBm의 <TEX>$P_{1dB}$</TEX>(1 dB gain compression point) 특성을 보였다. 그리고, 출력 전력 38.6 dBm에서 80.9 %의 최대 전력 부가 효율(Power Added Efficiency: PAE)을 나타냈으며, 이는 기존에 설계된 고효율 전력 증폭기와 비교했을 때 아주 우수한 효율 특성이다. 또한, W-CDMA 신호입력에 대한 측정 결과, 28.4 dBm의 평균 출력 전력에서 27.8 %의 PAE와 5 MHz offset 주파수에서 -38.8 dBc의 ACLR (Adjacent Channel Leakage Ratio)을 보였다. 그리고, 다항식 맞춤 방식의 디지털 전치 왜곡(Digital Predistortion: DPD) 선형화 알고리듬을 구현하여 제작된 전력 증폭기의 ACLR을 6.2 dB 정도 향상시킬 수 있었다. In this paper, we present the design, fabrication and measurement of high efficiency GaN HEMT power amplifier using harmonic matching technique. In order to achieve high efficiency, harmonic load-pull simulation is performed, that is, the optimum load impedances are determined at <TEX>$2^{nd}$</TEX> and <TEX>$3^{rd}$</TEX> harmonic frequencies as well as at the fundamental. Then, the output matching circuit is designed based on harmonic load-pull simulation. The measurement of the fabricated power amplifier shows the linear gain of 20 dB and <TEX>$P_{1dB}$</TEX>(1 dB gain compression point) of 33.7 dBm at 1.85 GHz. The maximum power added efficiency(PAE) of 80.9 % is achieved at the output power of 38.6 dBm, which belongs to best efficiency performance among the reported high efficiency power amplifiers. For W-CDMA input signal, the power amplifier shows a PAE of 27.8 % at the average output power of 28.4 dBm, where an ACLR (Adjacent Channel Leakage Ratio) is measured to be -38.8 dBc. Digital predistortion using polynomial fitting was implemented to linearize the power amplifiers, which allowed about 6.2 dB improvement of an ACLR performance.

5.65 GHz High-Efficiency GaN HEMT Power Amplifier With Harmonics Treatment up to Fourth Order

A high-efficiency GaN HEMT power amplifier with harmonics treatment up to the fourth order has been developed at the 5.8 GHz band. The harmonics treatment was applied by considering the influence of feedback and shunt capacitance in the GaN HEMT, to reduce the average power consumption in a GaN HEMT including parasitic elements. The fabricated GaN HEMT amplifier delivered a maximum power-added efficiency of 79% and a maximum drain efficiency of 90% at 5.65 GHz, and the saturated output power was 33.3 dBm. This value represents state-of-the-art C-band performance efficiency.