A load-pull-based behavioral model for Doherty PA design

Marbell, M.N.; Simcoe, M.; Wilson, Richard; Chidurala, M.; Ward, S.

doi:10.1109/wamicon.2011.5872868

Cited by 8 publications

(4 citation statements)

References 16 publications

(7 reference statements)

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“…In general, power amplifier design involves the tradeoff between different metrics, i.e., gain, noise, output power, nonlinear distortion and efficiency. Unfortunately, these metrics are optimal at different transistor load impedance values, which has been empirically observed using load pull techniques in both AB [25]- [27] and Doherty design [28], [29]. Hence, the power amplifier designer must choose the load impedance at transistor levels compromising between these metrics.…”

Section: A Power Amplifier Designmentioning

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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Section: A Power Amplifier Designmentioning

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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QC 20150123

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“…While these methodologies were found useful when designing single transistor based HPAs, they fall short in handling the complexity associated with the design of advanced HPA topologies that include more than one transistor such as Doherty Amplifiers and Load Modulated Balanced Amplifiers. This motivated the attempts to mobilize the use of behavioral models in the design of advanced HPA topologies [9] [10] [11] [12] [13].…”

Section: Introductionmentioning

confidence: 99%

A Time-Domain Multi-Tone Distortion Model for Effective Design of High Power Amplifiers

Amini

Boumaiza

2022

IEEE Access

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This paper proposes a new time-domain multi-tone distortion (TD-MTD) model suitable for accurately predicting the non-linear behavior of packaged high power radio frequency (RF) transistors over a range of discrete non-uniformly distributed frequencies. This proposed TD-MTD model uses a single expression rather than multiple distinct frequency specific behavioral models to describe the underlying behavior of the high power RF transistor at multiple fundamental frequencies. Furthermore its extraction is carried out using a time-domain representation of the travelling waves that can be acquired using a generic vector load-pull characterization system and without imposing additional requirements. The proposed model is extracted as an artificial neural network (ANN) and is implemented as a Netlist to serve in a harmonic balance simulator based power amplifier design process. The proposed model is validated in two phases. First, its ability to reproduce the large-signal behavior of a high power RF LDMOS transistor was demonstrated in simulation. Then, the TD-MTD model was used to validate the design of a high power two-way asymmetric Doherty power amplifier and the simulated output-power-dependent power efficiency, AM/AM, AM/PM and input return loss characteristics were compared to those obtained in measurement. The excellent agreement between the simulation and measurement results confirms the usefulness of the proposed model despite the simplicity of its extraction routine and measurement data.INDEX TERMS artificial neural network, behavioral model, computer-aided design, harmonic balance simulation, load-pull, measurement-based design, non-linear time-invariant model, poly-harmonic distortion model, power amplifier design, power transistor model, Volterra series

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“…To overcome this limitation, a method is introduced to extract the PHD model using load-pull so that the model can be used under all impedance conditions, calling this model a load-dependent PHD model, 34 which has demonstrated good results in PA design. [35][36][37] However, the model requires as many impedance conditions as possible, resulting in an excessively large file size for the resulting PHD model. In reference 38, a load-reflection magnitude-dependent model has been introduced, that can greatly reduce the model file size; however, interpolation is required for impedance conditions that are not included in the extracted range.…”

Section: Introductionmentioning

confidence: 99%

“…To overcome this limitation, a method is introduced to extract the PHD model using load‐pull so that the model can be used under all impedance conditions, calling this model a load‐dependent PHD model, 34 which has demonstrated good results in PA design 35–37 . However, the model requires as many impedance conditions as possible, resulting in an excessively large file size for the resulting PHD model.…”

Section: Introductionmentioning

confidence: 99%

Application of harmonic includedCPL‐QPHDmodel ofGaNdevice for broadbandPAdesign

Tang

Cai

2022

Int J RF Mic Comp-Aid Eng

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In this work, a harmonic included canonical piecewise linear (CPL) function based quadratic poly-harmonic distortion (QPHD) model is presented. The proposed model employs the framework of the standard QPHD model, making use of the CPL functions for interpolation of the amplitude of the dominant input signal. Compared with the standard QPHD model, the model described in this work is able to predict transistor behavior at different levels of input powers with one single set of model coefficients. The harmonic information has also been added in this model to make it more complete. The model is validated in terms of both DC and RF behavior through simulated data of a 10 W gallium nitride (GaN) high-electron-mobility transistor (HEMT) over a wide range of load conditions and power levels. In addition, the model is implemented in advanced design system (ADS) with frequency-defined device (FDD), and applied for a broadband power amplifier (PA) design. Chebyshev low-pass topology is used for both input and output matching network design. Finally, a broadband PA is implemented with an average power added efficiency of 66.23%, an average power of 41.09 dBm, and an average gain of 13.09 dB across the operating frequency range from 0.6 to 1.7 GHz. The simulation results of the harmonic included CPL-QPHD model are highly matched with the measurement results of the designed PA, demonstrating the feasibility of applying the proposed model for broadband PA design.

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A load-pull-based behavioral model for Doherty PA design

Cited by 8 publications

References 16 publications

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

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

A Time-Domain Multi-Tone Distortion Model for Effective Design of High Power Amplifiers

Application of harmonic includedCPL‐QPHDmodel ofGaNdevice for broadbandPAdesign

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