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A postmatching concurrent dual‐band Doherty power amplifier with enhanced bandwidth
Author(s) -
Meng Fan,
Zhu XiaoWei,
Xia Jing,
Yu Chao
Publication year - 2018
Publication title -
international journal of rf and microwave computer‐aided engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.335
H-Index - 39
eISSN - 1099-047X
pISSN - 1096-4290
DOI - 10.1002/mmce.21514
Subject(s) - predistortion , amplifier , bandwidth (computing) , linearity , materials science , electrical impedance , optoelectronics , gallium nitride , multi band device , electrical engineering , telecommunications , computer science , engineering , antenna (radio) , layer (electronics) , composite material
Abstract In this article, a postmatching concurrent dual‐band (C‐DB) Doherty power amplifier (DPA) is proposed to enhance the bandwidth in each frequency band. The relationship between the phases of carrier and peaking impedance inverting networks (IINs) and the bandwidth of the C‐DB DPA is analyzed for the first time. By designing the carrier and peaking IINs with appropriate minimum phase delays, the bandwidth of C‐DB DPA can be enhanced and balanced in both frequency bands. Based on postmatching technique, load impedance at the combining point is optimized by comparing the DPA's bandwidth at back‐off and saturation. A high‐efficiency C‐DB DPA working at 2.0‐2.4 and 3.2‐3.6 GHz (400 MHz bandwidth each) is designed and fabricated based on commercial gallium nitride HEMTs to validate the proposed technique. Measurement results show that the DPA has a 6 dB back‐off efficiency of 54%‐57% and a saturated efficiency of 70%‐71% at 2.0‐2.4 GHz. At 3.2‐3.6 GHz, the efficiency of 52%‐55% at 6 dB back‐off and 65%‐71% at saturation can be obtained. Modulated signals are also employed to excite the DPA at the two bands. The DPA can achieve an average efficiency of more than 47% at 7 dB back‐off with excellent linearity by utilizing digital predistortion.