Demystifying Envelope Tracking: Use for High-Efficiency Power Amplifiers for 4G and Beyond

Wang, Zhancang

doi:10.1109/mmm.2014.2385351

Cited by 57 publications

(17 citation statements)

References 36 publications

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“…The most popular load modulation solutions are the Doherty power amplifier [14] and the Chireix outphasing amplifier [15]. Concerning bias modulation, the Envelope Elimination and Restoration (EER) technique, also known as the Kahn technique [16], and the Envelope Tracking (ET) [17] technique are currently attracting major interest. More recently, advanced variations and combinations of these techniques, such as asymmetric multilevel outphasing [18], have been also reported.…”

Section: Back-off Efficiency Enhancement Techniquesmentioning

confidence: 99%

High Efficiency Power Amplifiers for Modern Mobile Communications: The Load-Modulation Approach

et al. 2017

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Abstract:Modern mobile communication signals require power amplifiers able to maintain very high efficiency in a wide range of output power levels, which is a major issue for classical power amplifier architectures. Following the load-modulation approach, efficiency enhancement is achieved by dynamically changing the amplifier load impedance as a function of the input power. In this paper, a review of the widely-adopted Doherty power amplifier and of the other load-modulation efficiency enhancement techniques is presented. The main theoretical aspects behind each method are introduced, and the most relevant practical implementations available in recent literature are reported and discussed.

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Section: Back-off Efficiency Enhancement Techniquesmentioning

confidence: 99%

High Efficiency Power Amplifiers for Modern Mobile Communications: The Load-Modulation Approach

et al. 2017

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“…More recently, Dalla Santa et al [27] have investigated an SOA bias current control strategy for optical equalization of the upstream in a PON system with four 25Gb/s channels and multilevel modulation format, the SOA being used as a pre-amplifier. Such adaptive biasing schemes actually shares some similarities with the popular envelope tracking (ET) technique [28] [29] used for inscreasing RF power amplifier efficiency, by modulating the supply voltage according to the input signal envelope fluctuation. Compared to digital baseband predistortion techniques, an ET scheme for linearizing SOA offers the advantage that it can be applied with a very similar approach whether SOA is used as a booster or as inline amplifier, with no strict requirement regarding the linearizer tuning (no learning stage).…”

Section: Introductionmentioning

confidence: 99%

A numerical assessment of an effective envelope-tracking semiconductor optical amplifier design for coherent-optical OFDM transmission

Ortiz-Cornejo

Morel

Azou

et al. 2020

Optics Communications

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The inherent nonlinear effects associated to Semiconductor Optical Amplifiers (SOAs) may translate into a transmission performance loss for non-constant envelope modulation formats. However, a variety of linearization schemes may be adopted for coping with these impairments and offering an effective system design. In this paper, an envelope tracking (ET) technique is investigated for linearizing an SOA-based Coherent Optical OFDM transmitter. An optimized design of the ET subsystem is performed under various scenarios, with the eventual joint use of Peak-to-Average Power Ratio (PAPR) reduction either via hard-clipping or nonlinear companding. A thorough carrier density analysis is performed in the amplifier, for various target gain values, so as to assess the effectiveness of the proposed scheme. Morever, we investigate the robustness of the proposed approach against some parameters variation both inside the ET path (DAC characteristics and bandwidth limited envelope generation). Extensive simulations performed with a precise SOA model show that up to 8 dB (resp. 7 dB) BER improvement can be achieved via the proposed scheme in the case of 4-QAM/OFDM (resp. 16-QAM/OFDM), compared to the conventional system with no linearization, and that even an envelope quantized with 2 bits still enables a significant performance increase.

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“…One drawback of the EER/polar and ET amplifiers is the dependency of supply modulator performance on the amplifier efficiency, bandwidth, peak power, and dynamic range, which, in practice, severely restricts the instantaneous modulation bandwidth [10]. The operation of the Doherty Power Amplifier (DPA) that was originally proposed by W. H. Doherty in 1936 [11] and Outphasing by H. Chireix [12] are based on an active load modulation mechanism. The Outphasing architecture performs linear amplification by nonlinear components and it provides efficiency levels of 20-60%, and bandwidths of up to 40 MHz.…”

Section: Introductionmentioning

confidence: 99%

A Survey on RF and Microwave Doherty Power Amplifier for Mobile Handset Applications

et al. 2019

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This survey addresses the cutting-edge load modulation microwave and radio frequency power amplifiers for next-generation wireless communication standards. The basic operational principle of the Doherty amplifier and its defective behavior that has been originated by transistor characteristics will be presented. Moreover, advance design architectures for enhancing the Doherty power amplifier’s performance in terms of higher efficiency and wider bandwidth characteristics, as well as the compact design techniques of Doherty amplifier that meets the requirements of legacy 5G handset applications, will be discussed.

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Demystifying Envelope Tracking: Use for High-Efficiency Power Amplifiers for 4G and Beyond

Cited by 57 publications

References 36 publications

High Efficiency Power Amplifiers for Modern Mobile Communications: The Load-Modulation Approach

High Efficiency Power Amplifiers for Modern Mobile Communications: The Load-Modulation Approach

A numerical assessment of an effective envelope-tracking semiconductor optical amplifier design for coherent-optical OFDM transmission

A Survey on RF and Microwave Doherty Power Amplifier for Mobile Handset Applications

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