Boundary Adjustment Hysteresis Current Control for Improving the Efficiency of Parallel-Form Switch-Linear Hybrid Envelope Tracking Power Supply

The parallel-form switch-linear hybrid envelope tracking power supply is usually composed of a buck converter with hysteresis current control (HCC) and a voltage-controlled linear amplifier (VLA) connected in parallel. The buck converter is aiming to provide most of the load current for minimizing the output current of VLA to reduce its power loss. However, when the load voltage swing is large, the voltage across VLA is high and thus its power loss is still significant. In this article, a boundary adjustment HCC method is proposed to reduce the voltages across the operating power devices, leading to decreased power loss of VLA and improved overall efficiency. A prototype with 10–27-V output voltage and 14-W average output power is fabricated and tested with both constant resistance and authentic power amplifier for tracking 10-MHz bandwidth envelope signal. The experimental results validated the proposed method.