An extended doherty amplifier with high efficiency over a wide range2472 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 maintains high efficiency over a wide range of output power ( 6 dB), is presented in this paper. This extended Doherty amplifier is demonstrated 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 maintaine……