A Comparative Study of Power Amplifiers' Sensitivity to Load Mismatch: Single Branch vs. Doherty Architectures

Messaoudi, Nizar; Hammi, Oualid; Sirois, J.; Boumaiza, Slim; Ghannouchi, Fadhel M.

doi:10.1109/ccece.2007.384

Cited by 7 publications

(5 citation statements)

References 15 publications

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“…Various PA topologies have been studied under mismatch. The DPA has been simulated in [7] and even compared with a class-AB amplifier in [8] for different reflection coefficients. Furthermore, a DPA was implemented and tested in a 8 × 1 transmitting array under beam-steering mismatch [9].…”

Section: Introductionmentioning

confidence: 99%

Investigation of power amplifier performance under load mismatch conditions

Argaez-Ramirez

Perez-Cisneros

Fager

2021

2021 IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications (PAWR)

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The time-varying loading conditions that power amplifiers (PAs) experience in active antenna systems degrade their overall performance. Consequently, the design of linear and highly-efficient PAs under mismatch is more important than ever. In this paper, different common and promising PA architectures, i.e. class-B, balanced, Doherty (DPA) and load-modulated-poweramplifier (LMBA), are analyzed under mismatch. Their sensitivity in terms of linearity, efficiency and output power is compared under a LTE signal excitation. Average drain efficiency (DE), average output power, normalized-mean-square-error (NMSE) as well as maximum output power variations are presented for each architecture as function of the voltage-standing-waveratio (VSWR). Thereby, the most suitable PA architecture to be integrated in active antenna systems may be identified.

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Section: Introductionmentioning

confidence: 99%

Investigation of power amplifier performance under load mismatch conditions

Argaez-Ramirez

Perez-Cisneros

Fager

2021

2021 IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications (PAWR)

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“…Therefore, it is of significant interest to the RF design community to develop a new modelling approach capable of predicting accurately the dynamic response of a PA when subjected to complex, digitally-modulated, wideband inputs, along with potentially large perturbations at the PA output due to dynamic effective load modulation. Indeed, the development of such models is an active research topic [8]- [19].…”

Section: Introductionmentioning

confidence: 99%

Behavioral Model of RF PAs Including Load Mismatch Effects Based on Canonical Section-wise Piecewise-Linear Function

Cai

King

2020

IEEE Access

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A new, dynamic, double-input, double-output (DIDO), wideband, dynamic, complex envelope, behavioral model for power amplifiers (PAs), accounting for load mismatch effects, is proposed and validated in this paper. The model is constructed based on two-dimensional, dynamic, canonical section-wise piecewise-linear functions (2-D DCSWPL). Compared with existing DIDO behavioral modeling methods, which are almost all exclusively based on polynomial functions, the proposed model permits a vastly extended modeling space for PAs under load mismatch conditions. Experimental examples are given to validate the proposed modeling technique with a 15 W GaN PA under a wide range of output mismatch conditions, driven by a 5 MHz LTE signal. The proposed model shows an average accuracy improvement of 2 dB when compared with the more traditional DIDO memory polynomial (MP) models. In addition, the load reflection-dependent dynamic 2-D CSWPL modeling technique for PAs under mismatch condition is also provided. Compared with load-dependent MP, load-dependent crossover MP (COMP) and load-dependent DIDO MP models, the proposed model shows superior accuracy. Thus, the proposed modeling technique is an excellent choice for the modelling of PA systems that are subject to load mismatch effects. INDEX TERMS Canonical section-wise piecewise-linear Function, dynamic modeling, load mismatch effects, nonlinear behavioral Modeling, RF PAs.

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“…A study of the effects of load impedance mismatch in different amplifier architectures was presented in [16], but the study did not include linearization techniques as DPD for the amplifiers. A sensitivity study of a DPD-linearized amplifier under mismatch conditions [14] showed large variations for different load impedances.…”

mentioning

confidence: 99%

Output Impedance Mismatch Effects on the Linearity Performance of Digitally Predistorted Power Amplifiers

Zenteno

Isaksson

Händel

2015

IEEE Trans. Microwave Theory Techn.

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This paper analyzes the effects of load impedance mismatch in power amplifiers which linearity has been enhanced using various digital predistortion (DPD) algorithms. Two different power amplifier architectures are considered: a class AB and a Doherty amplifier and three model structures for the DPD model are compared: memoryless polynomial (MLP), general memory polynomial (GMP) and Kautz-Volterra functions (KV). This paper provides a sensitivity analysis of the linearized amplifiers under load mismatch conditions and reports the performance when dynamic parameter identification for the DPD is used to compensate for the changes in the load impedance. In general,power amplifiers linearity is sensitive to load impedance mismatch. Linearity may degrade as much as 10 dB (in normalized mean square error) according to the magnitude and the phase of the reflection coefficient provided by the load impedance. However, depending on the amplifier design, the sensitivity toload impedance mismatch varies. While the Doherty amplifier studied show significant linearity degradations in the in-band and out-of-band distortions, the out-of-band distortions of the studied class AB were less sensitive to the load impedance mismatch. In adaptive DPD schemes, the performance obtained in the MLP model does not benefit from the updating scheme and the performance achieved is similar to a static case, where no updates are made. This stresses the memory requirements in the predistorter. When employing the GMP and the KV models in an adaptive DPD scheme, they tackle to a larger extent the linearity degradations due to load impedance mismatch.

QC 20150123

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A Comparative Study of Power Amplifiers' Sensitivity to Load Mismatch: Single Branch vs. Doherty Architectures

Cited by 7 publications

References 15 publications

Investigation of power amplifier performance under load mismatch conditions

Investigation of power amplifier performance under load mismatch conditions

Behavioral Model of RF PAs Including Load Mismatch Effects Based on Canonical Section-wise Piecewise-Linear Function

Output Impedance Mismatch Effects on the Linearity Performance of Digitally Predistorted Power Amplifiers

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