Series-parallel-form switch-linear hybrid envelope-tracking power supply to achieve high efficiency

Envelope tracking (ET) techniques have been used to improve the efficiency of power amplifiers in wireless communication systems. The switch-linear hybrid (SLH) ET power supply, which features both wide tracking bandwidth and high efficiency, has received a great deal of attention. In both series- and parallel-form SLH ET power supply, the power loss of the linear amplifier is relatively high. This paper proposes a series-parallel form for the SLH ET power supply, which includes two switched-mode converters and one linear amplifier, to reduce both the output voltage swing and output current of the linear amplifier, thus reducing the power loss of the linear amplifier. A current prediction control scheme is proposed to remove the current sensor in the switched-mode converter, achieving accurate control for high-frequency current. A prototype is built for 5 MHz wideband code division multiple access envelope signal tracking and 40 W peak output power. The tested efficiency of the proposed configuration is 80.4%, which is much higher than that of the series-form SLH ET power supply.