A Novel Adaptive Power Divider for High-Efficiency LTE Doherty Power Amplifier

A novel adaptive power-divider (APD) structure is introduced to overcome the limitations of practical Doherty power amplifiers (DPA). This technique provides a new structure for which the primary distinction from conventional structures is that it adjusts power division ratio to reduce the work load during measurement. Because the base station power amplifiers have a low efficiency due to the power back-off operation, efficiency enhancement techniques become very important. In this article, the efficiency simulation and measurements show that power-added efficiency of 52.5% can be achieved at 11-dB back-off. The power-added efficiency of an adaptive power-divider Doherty power amplifier is 5-10% larger than a conventional Doherty power amplifier. Furthermore, it is shown that this new structure can be used to improve the efficiency of the amplifier and bring a little effect of the third-order inter-modulation distortion.