A Triangular-Wave Current Control for Parallel-Form Switch-Linear Hybrid Envelope Tracking Power Supply to Achieve High Efficiency

The parallel-form switch-linear hybrid (SLH) envelope tracking (ET) power supply is composed of a linear amplifier and a switched-mode converter connected in parallel. When the output voltage has a large swing, the linear amplifier suffers relatively high power loss, leading to decreased overall efficiency. For solving this problem, this paper proposes a triangular-wave current control to optimize the operation of the power devices in the Class AB linear amplifier, thus reducing the voltage across the operating power device. The proposed method can also reduce the switching frequency of the switchedmode converter. The narrow pulse elimination method is proposed to further reduce the switching times. A prototype is fabricated and tested for tracking 10-MHz envelope signal with 10-V   27-V output voltage and 14-W average output power. The real RF PA is adopted for testing the performance of the designed ET power supply. The experimental results verify the effectiveness of the proposed methods.