A Series-Parallel-Form Switch-Linear Hybrid Envelope Tracking Power Supply With Two Multilevel Converters Sharing a Voltage-Level Provider

Series-parallel-form switch-linear hybrid envelope tracking power supply is composed of a voltage-controlled linear amplifier (VLA), a voltage-controlled switched-mode converter (VSC) and a current-controlled switched-mode converter. When the VLA adopts a class AB linear amplifier, an additional VSC can be added to be in series with the bottom transistor of the VLA to reduce its voltage drop. In order to reduce the system complexity, this article proposes to employ multiple bidirectional converters to implement the voltage-level provider, for being shared by the two VSCs, which are implemented with multilevel converters. Then, the loss model of the system is established, and based on which, an optimized design of the voltage-level number and voltage-level values of the multilevel converters is presented for improving the overall system efficiency. Finally, a prototype is fabricated aiming for tracking the envelope signal with 10-MHz bandwidth, 9.6–26.4-V output voltage, and 20-W average output power. The measured system efficiency is 78.79%, an improvement by 2.58% with the additional VSC.