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2472 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 49, NO. 12, DECEMBER 2001 An Extended Doherty Amplifier With High Efficiency
 

Summary: 2472 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 49, NO. 12, DECEMBER 2001
An Extended Doherty Amplifier With High Efficiency
Over a Wide Power Range
Masaya Iwamoto, Student Member, IEEE, Aracely Williams, Pin-Fan Chen, Member, IEEE,
Andre G. Metzger, Student Member, IEEE, Lawrence E. Larson, Fellow, IEEE, and Peter M. Asbeck, Fellow, IEEE
Abstract--An extension of the Doherty amplifier, which main-
tains high efficiency over a wide range of output power ( 6 dB), is
presented in this paper. This extended Doherty amplifier is demon-
strated experimentally with InGaP/GaAs heterojunction bipolar
transistors at 950 MHz. Power-added efficiency (PAE) of 46% is
measured at 1dB of 27.5 dBm and 45% is measured at 9 dB
backed off from 1dB. Additionally, PAE of at least 39% is main-
tained for over an output power range of 12 dB backed off from
1dB. This is an improvement over the classical Doherty ampli-
fier, where high efficiency is typically obtained up to 56 dB backed
off from 1dB. Compared to a single transistor class-B amplifier
with similar gain and 1dB, the extended Doherty amplifier has
PAE 2.6 higher at 10 dB back off and 3 higher at 20 dB back
off from 1dB. Under different bias and output matching condi-
tions, the amplifier was also evaluated with CDMA signals. At the

  

Source: Asbeck, Peter M. - Department of Electrical and Computer Engineering, University of California at San Diego
Larson, Larry - Department of Electrical and Computer Engineering, University of California at San Diego

 

Collections: Engineering