In this work, a premise is applied to the conventional load modulation equation of Doherty power amplifier (DPA) in 0.25 m GaAs pHEMT technology to compensate output impedance of main amplifier ( Z out,main ) variation, even in low power region. Using this modified modulation leads to the DPAs power added efficiency (PAE) increase in comparison by the case in which the load modulation revision is ignored, which is also designed in this paper. Second harmonic rejection networks are also added to both designs to play their roles as to efficiency increase. By doing so, the revised load modulation based DPA has the maximum PAE of 39.6%, maximum output power ( P out ) of 31.61dBm, at 8 GHz. Simulation results of this DPA in higher harmonics indicate the designed DPA has the minimum second and third harmonics power of -51.7 dBm and -80 dBm, respectively. For the sake of linearity evaluation, it is depicted that 1dB-power gain compression has not occurred in the input power (P in ) range in which the proposed DPA works.
Author and article information
] Iran University of Science and Technology
This work has been published open access under Creative Commons Attribution License
CC BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided
can be found at