Summary: 1244 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 53, NO. 4, APRIL 2005
Design of Wide-Bandwidth Envelope-Tracking
Power Amplifiers for OFDM Applications
Feipeng Wang, Student Member, IEEE, Annie Hueiching Yang, Student Member, IEEE,
Donald F. Kimball, Member, IEEE, Lawrence E. Larson, Fellow, IEEE, and Peter M. Asbeck, Fellow, IEEE
Abstract--An efficiency-enhanced power-amplifier system
design is presented based on wide-bandwidth envelope tracking
(WBET) with application to orthogonal frequency-division multi-
plexing wireless local area network systems. Envelope elimination
and restoration (EER) and WBET are compared in terms of the
time mismatch sensitivity between the base-band amplitude path
and the RF path, and it is demonstrated that WBET is much less
sensitive than EER to these effects. An adaptive time-alignment
algorithm for the WBET system is developed and demonstrated.
The analysis and algorithm are verified by experimental results.
The measurement shows that the peak drain efficiency of the com-
plete system was 30% at a 2.4-GHz orthogonal frequency-division
multiplexing output power of 20 dBm.
Index Terms--Envelope elimination and restoration (EER), en-
velope tracking (ET), orthogonal frequency-division multiplexing