High-Efficiency Switch-Linear-Hybrid Envelope-Tracking Power Supply With Step-Wave Approach

Featuring high bandwidth and high efficiency, the switch-linear hybrid envelope tracking (SLH-ET) power supply has been gaining considerable attentions. This paper proposes a new configuration for SLH-ET power supply, which consists of a switching-mode converter with a step-wave approach and a linear amplifier connected in parallel. The switches in the switching-mode converter are operated only one time in every tracking period, leading to reduced switching loss and, thus, a higher efficiency. The number of the voltage levels and the voltage difference between the adjacent steps are analyzed in terms of the voltage synthesis accuracy and voltage total harmonic distortion. A full feedforward of the output voltage scheme is adopted to make the switching-mode converter provide the most load power and the linear amplifier only provide the ripple current that resulted by the switching-mode converter. Thus, the overall efficiency is improved. A prototype is built aiming for 300-kHz sine-wave tracking, with a 10-26-V output voltage and a 50-W peak output power. The experimental results show that the proposed configuration can obtain higher efficiency as well as high tracking bandwidth.