A Dual-Input Digitally Driven Doherty Amplifier Architecture for Performance Enhancement of Doherty Transmitters

作者：Darraji Ramzi^*; Ghannouchi Fadhel M; Hammi Oualid

来源：IEEE Transactions on Microwave Theory and Techniques, 2011, 59(5): 1284-1293.

DOI：10.1109/TMTT.2011.2106137

• Digital adaptive phase alignment
• dual-input Doherty power amplifier (PA)
• gallium nitride (GaN)
• load modulation
• power-added efficiency (PAE)

In this paper, the novel architecture of a dual-input and digitally driven Doherty amplifier is proposed with the aim of improving the performance of gallium-nitride (GaN) Doherty transmitters. In this work, the power efficiency is enhanced by using digital adaptive phase alignment to compensate for performance degradation due to bias and power-dependant phase misalignment between the carrier and peaking branches. For experimental validation, the proposed dual-input digital Doherty power amplifier (PA) was implemented using a 10-W GaN transistor. Measurement results demonstrate that the dual-input Doherty prototype exhibited a power-added efficiency (PAE) higher than 50% over an 8-dB output power back-off (OPBO) range. In comparison with the conventional fully analog Doherty PA, this represents a 10% improvement in PAE over the same OPBO range. Using a one-carrier Worldwide Interoperability for Microwave Access signal with a 7-dB peak-to-average power ratio, the dual-input Doherty PA, with digital adaptive phase alignment applied at the input of its peaking path, achieved a PAE of 57% at an average output power of 37.8 dBm, along with a -22-dBc adjacent channel power ratio (ACPR). This corresponds to an improvement of 7% in PAE and 1 dB in average output power for the same ACPR level in comparison with a conventional fully analog Doherty PA.

• 出版日期2011-5
• 单位中国石油大学（北京）