Linearization Technology For Wideband Envelope Tracking Power Amplifiers

With the development of wireless communication technology,the bandwidth of modulated signal is becoming wider and wider to increase the spectrum efficiency and data transmission rate.The wideband modulated signal usually exibits the high peak-to-average power ratio,leading to more challenges in efficiency of power amplifier(PA).Envelope tracking(ET)architecture is one of the most promising candidates to improve the efficiency,which is composed of a supply modulator and a PA.However,the main limitation is the bandwidth of the supply modulator.This thesis innovatively proposes linearization techniques based on memoryless and memory envelope to reduce the requirement of supply modulator bandwidth and simultaneously maintain the efficiency and linearity,which have been effectively validated by simulations and experiments.Firstly,the linearization technique based on memoryless envelope is proposed for scenarios that have high requirements on linearity.This technique theoretically analyzes the memoryless envelope from the point of view of the bandwidth reduction and tracking accuracy,and proposes a derivative-based memoryless envelope design technique.The memoryless envelope designs can be classified into two categories:envelope design with monotonous derivative and the one with non-monotonous derivative.Two examples are demonstrated to validate this method.The single-input-single-output model is applied in digital predistortion.The results of simulations and experiments have shown that the proposed technique can make a good tradeoff between bandwidth requirement and efficiency,while the ET PA can be effectively linearized.Then,the linearization technique based on memory envelope is proposed for scenarios where the bandwidth of supply modulator is further limited.The type?memory envelope design is firstly proposed,followed by the type?memory envelope design to further increase the efficiency.And the dual-input-single-output model is employed to linearize the ET PA under the memory envelope.Experiment results on the platform operated at Sub-6GHz and millimeter wave frequency band have shown that compared to the linearization technique based on memoryless envelope,the proposed technique can further reduce the envelope bandwidth to 1.2x B_RF while maintaining the efficiency,but the linearity will slightly change.Part of the above research results have been published in 2020 IEEE MTT-S International Wireless Symposium(IWS).