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| Full Feed-Forward of the Output Voltage Scheme for Envelope Tracking Power Supply Using Switch-Linear Hybrid Configuration |
| Xi Huan, Jin Qian, Ruan Xinbo, Xiong Xiaoling |
| Nanjing University of Aeronautics and Astronautics Nanjing 210016 China |
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Abstract To improve the efficiency of the power amplifier used in modern wireless communication system, a class AB linear amplifier and a synchronous Buck converter connected in parallel is presented in this paper to construct the envelope tracking (ET) power supply. The linear amplifier, with voltage-controlled feature, tracks the reference voltage waveform; the Buck converter, with current-controlled type, provides the most part of the load power. In order to eliminate the influences from the output voltage to the linear amplifier output current, the full feed-forward of the output voltage scheme is proposed in this paper. There are two feed-forward terms in this scheme, which counteract the two load admittances of the linear amplifier respectively, sequentially decrease the linear amplifier output current substantially. To verify the effectiveness of the proposed scheme, an ET prototype with 100 kHz sine wave tracking, 5～15V output voltage and 75 W peak output power is fabricated in the lab. Experimental results indicate that the full feed-forward of the output voltage scheme can basically remove the fundamental wave current component from the linear amplifier output current, which greatly improves the ET power supply efficiency.
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Received: 12 November 2011
Published: 25 March 2014
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2013, Vol. 28 
