Three-Stage Load Modulated Power Amplifier With Efficiency Enhancement at Power Back-Off

Title: Three-Stage Load Modulated Power Amplifier With Efficiency Enhancement at Power Back-Off
Authors: Xu, Y. (Yang)Pang, JingzhouWang, XiaoyuZhu, Anding
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Date: 8-Mar-2021
Online since: 2021-03-10T17:35:55Z
Abstract: This article presents the analysis and design of a three-stage load modulated power amplifier (PA), in which three amplifiers, each with different biasing, are connected to a four-port coupler. It is illustrated that, by properly configuring current relationships between the three amplifiers, this new load modulated PA can provide flexible output power back-off (OBO) and achieve high efficiency within a large OBO range. A detailed theoretical analysis and design methodology are given. In this architecture, the OBO level can be adjusted by simply setting bias conditions of the relevant amplifiers that correspond to the current relationships. Therefore, after circuit fabrication, the OBO range can still be reconfigured without redesigning the circuit. To validate the proposed approach, a prototype operating at 3.45 GHz is demonstrated and implemented with gallium nitride (GaN) transistors. The measured saturated output power reaches 45 dBm with 70.1% drain efficiency. At 6-/8-/10-dB OBO, the fabricated PA can provide up to 62.1%/53.8%/47.3% drain efficiency, respectively. When driven by a 60-MHz 9-dB peak-to-average power ratio (PAPR) long-term evolution (LTE) signal, the PA provides 34-dBm average output power with 44.3% average efficiency. Moreover, measurement results prove that the PA can offer efficiency enhancement when the OBO is reconfigured to 8 or 12 dB after fabrication.
Funding Details: European Commission Horizon 2020
Science Foundation Ireland
Type of material: Journal Article
Publisher: IEEE
Journal: IEEE Transactions on Microwave Theory and Techniques
Copyright (published version): 2021 IEEE
Keywords: ImpedanceModulationCouplersPower generation
DOI: 10.1109/tmtt.2021.3061436
Language: en
Status of Item: Peer reviewed
ISSN: 0018-9480
This item is made available under a Creative Commons License:
Appears in Collections:Electrical and Electronic Engineering Research Collection

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