Title :
An Improved Power-Added Efficiency 19-dBm Hybrid Envelope Elimination and Restoration Power Amplifier for 802.11g WLAN Applications
Author :
Wang, Feipeng ; Kimball, Donald F. ; Popp, Jeremy D. ; Yang, Annie Hueiching ; Lie, Donald Y. ; Asbeck, Peter M. ; Larson, Lawrence E.
Author_Institution :
Dept. of Electr. & Comput. Eng., Univ. of California at San Diego, La Jolla, CA
Abstract :
A comparison of envelope elimination and restoration (EER) and envelope tracking (ET) is discussed and a "hybrid" wideband EER power amplifier (PA) for the WLAN 802.11g system is proposed. A 60% efficiency (the output envelope signal power/input dc power) DC-20-MHz wideband envelope amplifier is designed for wideband EER and wideband ET (WBET) applications. A design method is developed to optimize the efficiency of the envelope amplifier for a given peak-to-average ratio and average slew rate of the envelope signal. An experimental "hybrid" Class-E EER system shows an overall efficiency (modulated RF output power/envelope amplifier dc input power) of 36% and power-added efficiency (the modulated RF output power/envelope amplifier dc input power plus RF input power) of 28% for a WLAN 802.11g signal at 19-dBm (80 mW) output power at 2.4 GHz. Digital predistortion, time alignment, and memory effect mitigation are implemented. The measured 3% error vector magnitude exceeds the 802.11g specification for 5% for a 54-Mb/s modulation signal
Keywords :
UHF power amplifiers; wideband amplifiers; wireless LAN; 2.4 GHz; 80 mW; 802.11g WLAN applications; Class-E EER system; dc-dc converter; delta-modulation; digital predistortion; envelope tracking; hybrid envelope elimination; hybrid wideband EER power amplifier; memory effect mitigation; restoration power amplifier; time alignment; wideband envelope amplifier; Broadband amplifiers; Design methodology; Power amplifiers; Power generation; Power system restoration; Radio frequency; Radiofrequency amplifiers; Signal design; Signal restoration; Wireless LAN; Class E; dc–dc converter; delta-modulation (DM); digital predistortion; envelope elimination and restoration (EER); envelope tracking (ET); hysteresis control; memory effect; modulator; orthogonal frequency-division multiplexing (OFDM); polar transmitter; power amplifiers (PAs); power tracking; pulsewidth modulation (PWM); time alignment; wireless local area network (WLAN);
Journal_Title :
Microwave Theory and Techniques, IEEE Transactions on
DOI :
10.1109/TMTT.2006.885575
