A Review of Efficiency Improvement Techniques in Modern Communication Systems

This paper discusses Doherty Power Amplifier(DPA) and its evolution over the years. The basic operational principle of the Doherty amplifier and its defective behavior that has been originated by transistor characteristics will be presented. The different research trends, all aimed to improve the advantages of the Doherty scheme and to solve its inherent drawbacks, are discussed.

A planner Doherty power amplifier with harmonic suppression with open and short ended stubs

This paper presents a new Doherty power amplifier (DPA) with harmonics suppression. A Wilkinson power divider (WPD) with open-ended and short-ended stubs is designed to suppress unwanted signals. To design the power divider in the circuit of the DPA, even and odd mode analyses are utilized. The proposed design operates at range of 1.2–1.6 GHz. The linearity of the suggested DPA is increased about 6 dBm, in comparison with the main amplifier. The designed Doherty amplifier has a power added efficiency (PAE), drain efficiency (DE) and Gain about 60, 61% and 19 dB, respectively. The designed WPD suppresses 2nd up to 14th harmonics with more than 20 dB suppression level, which is useful for suppressing unwanted harmonics in DPA design. ATF-34143 transistors (pHEMT technology) are used for this DPA amplifier design. The main amplifier has class-F topology and class-F inverse topology is used for auxiliary amplifier.