Highly efficient Doherty amplifier with peaking cell controlled using optimized shaped gate voltage

In this paper, the optimum gate control for a peaking cell of a Doherty amplifier is proposed. The proposed gate voltage waveform based on a variation in transcoductance provides a sufficient fundamental current for a peaking cell, which is relevant to the performance of a carrier cell. For further verification, a Doherty amplifier controlled by the proposed method and targeting a 3G LTE base station at 2.6 GHz has been fabricated using a commercially available 120 W GaN (Gallium Nitride) device. The amplifier provides a drain efficiency of 49.2% at an average output power of 45.6 dBm with an 8.5 dB PAPR signal maintaining an adjacent channel leakage power ratio of −48 dBc through digital pre-distortion (DPD) functionality.