Title :
Digitally Assisted Dual-Switch High-Efficiency Envelope Amplifier for Envelope-Tracking Base-Station Power Amplifiers
Author :
Hsia, Chin ; Zhu, Anding ; Yan, Jonmei J. ; Draxler, Paul ; Kimball, Donald F. ; Lanfranco, Sandro ; Asbeck, Peter M.
Author_Institution :
Dept. of Electr. & Comput. Eng., Univ. of California at San Diego (UCSD), La Jolla, CA, USA
Abstract :
This paper presents a novel digitally assisted dual-switch envelope amplifier used for wideband high-efficiency envelope-tracking (ET) base-station power amplifiers (PAs). The proposed envelope amplifier comprises two switching buck converters to provide the high-power ET signal to the RF stage and a wideband linear stage to maintain the envelope signal accuracy. The control technique utilizes digital signal processing in conjunction with analog hysteretic feedback to separately control two high-efficiency switchers and thus successfully reduces power consumption of the linear stage, especially for applications requiring high peak-to-average ratio (PAPR) signals. The overall ET system was demonstrated using GaAs high-voltage HBT PAs. For a variety of signals ranging from 6.6- to 9.6-dB PAPR and up to 10-MHz RF bandwidth, the overall system power-added efficiency reached 50%-60%, with a normalized root-mean-square error below 1% and the first adjacent channel leakage power ratio of -55 dBc after digital predistortion with memory mitigation, at an average output power above 20 W and 10-dB gain.
Keywords :
distortion; mean square error methods; power amplifiers; radiofrequency amplifiers; switching convertors; wideband amplifiers; ET base-station power amplifiers; PAPR signals; RF bandwidth; RF stage; adjacent channel leakage power ratio; analog hysteretic feedback; control technique; digital predistortion; digital signal processing; digitally assisted dual-switch envelope amplifier; digitally assisted dual-switch high-efficiency envelope amplifier; envelope signal accuracy; high-efficiency switchers; high-power ET signal; high-voltage HBT PA; memory mitigation; normalized root-mean-square error; output power; overall ET system; overall system power-added efficiency; peak-to-average ratio signals; power consumption; switching buck converters; wideband high-efficiency envelope-tracking base-station power amplifiers; wideband linear stage; Multiaccess communication; Peak to average power ratio; Power amplifiers; Predistortion; Digital predistortion; dynamic supply modulator; envelope tracking (ET); memory effects; peak-to-average power ratio (PAPR); power amplifiers (PAs);
Journal_Title :
Microwave Theory and Techniques, IEEE Transactions on
DOI :
10.1109/TMTT.2011.2166084