Hysteresis Voltage Prediction Control For Envelope Tracking Power Supply

In modern wireless communication systems,the envelope tracking(ET)technique can be adopted to dynamically regulate the supply voltage of the linear amplifier(LPA)according to the radio-frequency envelope,and thus significantly improve the efficiency of the LPA.As the key component in the ET system,ET power supply should have high tracking bandwidth and high efficiency.The switch-linear hybrid(SLH)ET power supply integrates the advantages of high efficiency of the switching-mode converter and wide bandwidth of the linear amplifier,and has become the mainstream structure of ET power supply.This paper is dedicated to the control method for the switching-mode converter in the series-form SLH ET power supply for achieving a high efficiency and a high bandwidth.In the series-form SLH ET power supply,the output voltage of the switched-mode converter is expected to synthesize the load voltage to reduce the power loss of the linear amplifier.The waveform of the output voltage of the switched-mode converter can be stepwave or continuous-wave.Apparently,a continuous-wave can mimic the envelope better.The buck converter is a good candidate for the the switched-mode converter thanks to its simple topology,and the hysteresis voltage control can be used for its good robustness.However,due to the LC filter,the output voltage of buck converter will exceed hysteresis borders,resulting in a lower efficiency and linearity of the ET power supply.This thesis proposes a hysteresis voltage prediction control for the buck converter,which determines the switching status of the power switch by predicting the variation of the output voltage,and thus limits the output voltage within the hysteresis boundaries.A prototype of the SLH ET power supply with the buck converter,aiming for 1 MHz tracking bandwidth,with 20 W average output power and 9.6 V ～ 26.4 V output voltage range,is built and tested in the lab,and the experimental results are provided to verify the effectiveness of the proposed hysteresis voltage prediction control.For the radio-frequency envelope with a higher bandwidth,the load voltage has a wide range of slew rates since it contains abundant components located in a wide frequency range.To mimic the load voltage,the switching frequency of buck converter will be extremely high,causing a huge switching loss.So,a multilevel converter is adopted instead of the buck converter,which can adjust the slew rate of its output voltage according to that of the load voltage by choosing appropriate voltage levels.The hysteresis voltage prediction control is proposed for the multilevel converter.A prototype of the SLH ET power supply with the multilevel converter is built and tested in the lab,aiming for 5 MHz tracking bandwidth,with 20 W average output power and 9.6 V～26.4 V output voltage range,and the experimental results are also presented.Finally,an ET system with the series-form SLH ET power supply is fabricated in the lab,and the experimental results are provided to verify the effectiveness of the proposed configuration and the voltage control strategies.