Design and simulation of a Doherty power amplifier for the base station

In order to solve the conflict between the efficiency and the linearity of a power amplifier in the base station, the Doherty structure is adopted to design the power amplifier in this paper. The problem is successfully solved in Agilent's ADS design platform by incorporating with the load-pull technology. A single amplifier, a balanced amplifier and a Doherty amplifier are designed in this work, which are used in the base station driver amplifier in the 920MHz-960MHz frequency band. The power-added efficiency of the Doherty amplifier can reach 48.9% when the peak output power backs off 6dB, with increase of 14.6% compared with the balanced amplifier. Besides, the third-order inter-modulation distortion is below -30dBc with the improvement of 4.9dB as well. The Doherty power amplifier is proved to have higher efficiency and good linearity from the simulation experiment, thus the structure can be well applied to the design of RF power amplifiers, which has an important reference value for PA designers.