毫米波氮化镓包络跟踪功率放大器实验研究

Experimental Research on Millimeter Wave GaN Envelope Tracking Power Amplifier

为了提高毫米波功率放大器的回退效率并拓展工作带宽,文中对毫米波频段氮化镓包络跟踪(Envelope Tracking,ET)功率放大器进行了实验研究。采用0.15μm氮化镓工艺的功放芯片,由线性电源调制器馈电,进一步采用数字预失真技术改善输出波形的非线性失真来提高线性电源调制器的工作带宽,最终在提高功放芯片效率的同时提升了其线性度。实验测试结果表明,在23~28 GHz频率范围内,当分别采用40MHz带宽峰均比为8.6 dB和80 MHz带宽峰均比为6.4 dB的正交频分复用(OFDM)64QAM调制信号进行测试时,恒压供电的功率放大器的回退效率分别为7.5%~10.1%和12.3%~16.5%,而采用线性电源调制器供电的ET功放回退效率为9.6%~14.3%和16.3%~22.1%,平均提升3%~6%左右,经过数字预失真处理后的邻近信道功率泄漏比均低于-30.1 dBc。

In order to improve the power back-off(PBO)efficiency and bandwidth of millimeter wave power amplifier(mm-wave PA),a mm-wave GaN envelope tracking(ET)power amplifier is experimentally studied in this paper.The 0.15μm GaN process power amplifier chip is supplied with the linear power supply modulator and the digital pre-distortion(DPD)technology is further used to improve the nonlinear distortion of the output waveform for improving the working bandwidth of the linear power supply modulator.Finally,the linearity of the power amplifier chip is improved while ensuring the high efficiency of the power amplifier chip.The tested results show that when driven by a 40 MHz OFDM with a peak to average ratio of 8.6 dB and an 80 MHz with a peak to average ratio of 6.4 dB signals respectively,the PBO efficiency of mm-wave PA with constant voltage power supply and linear supply modulator power supply are 7.5%-10.1%,12.3%-16.5%and 9.6%-14.3%,16.3%-22.1%.The PBO efficiency is increased by 3%-6%.After using DPD technology,the adjacent channel power leakage ratio of mm-wave PA is less than-30.1 dBc。