| Summary: | 碩士 === 國立臺灣大學 === 電機工程學研究所 === 103 === In this thesis, an envelope tracking power supply (ETPS) using envelope tracking tecknique is proposed to improve the efficiency of a linear power amplifier by producing a changeable voltage supply instead of the conventional constant voltage supply. In an envelope tracking power amplifier system, the nonsynchronization of the two voltages, envelope output produced by the ETPS and amplified signal produced by the power amplifier, causing the problem of degrading the power amplifier efficiency. Delaying the transmitted original signal for a delay time to synchronize two voltages remains the general solution. However, the delayed signal may not be totally identical to the original signal due to the signal processing. Therefore, a solution which the original signal without being processed named leading envelope signal scheme with a simple implemented phase lead circuit to synchronize two voltages is proposed in this thesis. In addition, mathematical analysis and circuit simulations are carried out to discuss the factors of the phase difference caused by the proposed ETPS between the envelope output and the envelope signal of the original signal. Finally, the hardware implementation of a 25W Buck type ETPS operating at 1MHz switching frequency is proposed to verify the feasibility of the ETPS and leading envelope signal scheme.
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