Multiplexing the Level Provider of Multilevel Converters in Series-Parallel-Form Switch-Linear Hybrid Envelope Tracking Power Supply

Series-parallel-form switch-linear hybrid (SLH) envelope tracking (ET) power supply is composed of a current-controlled switched-mode converter (CSC), a voltage-controlled switched-mode converter (VSC), and a voltage-controlled linear amplifier (VLA). When the VLA adopts a class-AB linear amplifier, it has two power switches, and the VSC could only reduce the voltage imposed on the top switch, yet the bottom switch suffers a large voltage drop, which deteriorates the system efficiency. In order to decrease the loss of the bottom switch, another VSC, named as VSC2, is introduced between the bottom switch and the power ground to reduce the voltage imposed on the bottom switch. Furthermore, this paper proposes to multiplex the level provider of the multilevel converters, reducing the volume and complexity of the system. Then, an optimized method to decrease the equivalent switching frequencies of multilevel converters is presented. Finally, a simulation platform is implemented for 20-MHz bandwidth LTE envelope tracking, with 9.6$\sim$26.4V output voltage and 20 W average output power. The simulation results verify the effectiveness of the proposed topology and optimized method.