A Broadband Doherty-like Power Amplifier with Large Power Back-off Range

Zhiwei Zhang, Vincent Fusco, Zhiqun Cheng, Chao Gu, Neil Buchanan, Jiajie Ying

Research output: Contribution to journalArticlepeer-review


This paper proposes a novel power amplifier (PA) topology which can realize PA operation with high power back-off range (OBO) and wide bandwidth. Here a short-circuit reactance instead of an additional PA branch is introduced into the isolated port of a coupler to provide the frequency dependency required for broadband load impedance modulation. In addition, the corresponding complex load impedances at each normalized frequency are given to achieve high OBO based on the use of the same transistor in both the carrier PA and peak PA branches. The behaviours of the proposed PA as a function of input power are also derived based on the appropriate complex load impedance. To validate the proposed topology, a PA with 9 dB OBO operating across 1.0-3.0 GHz is designed, fabricated, and tested. Measurements illustrate that the PA can deliver a saturated output power from 44 dBm to 45 dBm over 1.0-3.0 GHz, with a drain efficiency ranging from 62% to 71%. Drain efficiencies are from 41% to 48% at the OBO of 9 dB.
Original languageEnglish
Number of pages5
JournalIEEE Transactions on Circuits and Systems II: Express Briefs
Early online date14 Feb 2022
Publication statusEarly online date - 14 Feb 2022


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