A Fully Integrated C-Band GaN MMIC Doherty Power Amplifier With High Efficiency and Compact Size for 5G Application

Authors:
Open Access
Publisher website
Google Scholar
Abstract
This paper presents a fully integrated C-band Doherty power amplifier (DPA) based on a 0.25-μm GaN-HEMT process for 5G massive MIMO application. The performance degradation caused by nonlinear output capacitance is analyzed, and a novel compensation technique is proposed. A low-Q output network is employed to broaden the bandwidth, and its insertion loss in the back-off region is demonstrated to be mainly decided by the Q-factor of the drain bias inductor of the main PA. Hence, by adopting on-chip transmission lines with high Q-factors for drain biasing, a full integration and a low loss can be achieved simultaneously. Reversed uneven power splitting and back-off input matching are proposed for gain enhancement. The fabricated DPA demonstrates a small-signal gain of 8.6 -11.6 dB, an output power of 40.4 -41.2 dBm, a 6-dB back-off drain efficiency (DE) of 47% -50%, and a saturation DE of 55% -63% across a wide bandwidth from 4.5 to 5.2 GHz, with an ultra-compact size of 2.2 mm × 2.1 mm. Using a 40-MHz LTE signal with a 7.7-dB peak-to-average power ratio at the carrier frequency of 4.9 GHz, the measured average output power and efficiency are 33 dBm and 43%, respectively. The raw adjacent channel power ratio is -29 dBc, and is improved to -46 dBc by applying digital predistortion.
Funding Information
  • National Key Research and Development Program of China (2016YFB0400200)
  • National Key Research and Development Program of China (2017YFF0206201)
  • National Science and Technology Major Project (2017ZX03001024)
  • National Natural Science Foundation of China (61522112)
  • National Natural Science Foundation of China (61331003)
  • Beijing National Laboratory for Information Science and Technology

This publication has 32 references indexed in Scilit: