X-Parameter Based Modelling of Polar Modulated Power Amplifiers

Yelin Wang, Troels Studsgaard Nielsen, Daniel Sira, Ole Kiel Jensen, Torben Larsen

Research output: Contribution to journalJournal articleResearchpeer-review

3 Citations (Scopus)

Abstract

X-parameters are developed as an extension of S-parameters capable of modelling non-linear devices driven by large signals. They are suitable for devices having only radio frequency (RF) and DC ports. In a polar power amplifier (PA), phase and envelope of the input modulated signal are applied at separate ports and the envelope port is neither an RF nor a DC port. As a result, X-parameters may fail to characterise the effect of the envelope port excitation and consequently the polar PA. This study introduces a solution to the problem for a commercial polar PA. In this solution, the RF-phase path is modelled by X-parameters and the envelope path of the polar PA is simulated by a low-pass filter. The solution can be applied to a group of polar PAs who have the similar topology and design as the one in this work. Modulated signals with different channel bandwidths were applied to the model of the polar PA for simulations. The simulated error vector magnitude (EVM) and adjacent channel power ratio (ACPR) were compared with the measured data to validate the model. The maximum differences between the simulated and measured EVM and ACPR are less than 2% point and 3 dB, respectively.
Original languageEnglish
JournalIET Microwaves, Antennas & Propagation
Volume7
Issue number14
Pages (from-to)1161 - 1167
ISSN1751-8725
DOIs
Publication statusPublished - 2013

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Power amplifiers
Low pass filters
Scattering parameters
Topology
Bandwidth

Cite this

Wang, Yelin ; Nielsen, Troels Studsgaard ; Sira, Daniel ; Jensen, Ole Kiel ; Larsen, Torben. / X-Parameter Based Modelling of Polar Modulated Power Amplifiers. In: IET Microwaves, Antennas & Propagation. 2013 ; Vol. 7, No. 14. pp. 1161 - 1167.
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title = "X-Parameter Based Modelling of Polar Modulated Power Amplifiers",
abstract = "X-parameters are developed as an extension of S-parameters capable of modelling non-linear devices driven by large signals. They are suitable for devices having only radio frequency (RF) and DC ports. In a polar power amplifier (PA), phase and envelope of the input modulated signal are applied at separate ports and the envelope port is neither an RF nor a DC port. As a result, X-parameters may fail to characterise the effect of the envelope port excitation and consequently the polar PA. This study introduces a solution to the problem for a commercial polar PA. In this solution, the RF-phase path is modelled by X-parameters and the envelope path of the polar PA is simulated by a low-pass filter. The solution can be applied to a group of polar PAs who have the similar topology and design as the one in this work. Modulated signals with different channel bandwidths were applied to the model of the polar PA for simulations. The simulated error vector magnitude (EVM) and adjacent channel power ratio (ACPR) were compared with the measured data to validate the model. The maximum differences between the simulated and measured EVM and ACPR are less than 2{\%} point and 3 dB, respectively.",
author = "Yelin Wang and Nielsen, {Troels Studsgaard} and Daniel Sira and Jensen, {Ole Kiel} and Torben Larsen",
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X-Parameter Based Modelling of Polar Modulated Power Amplifiers. / Wang, Yelin; Nielsen, Troels Studsgaard; Sira, Daniel; Jensen, Ole Kiel; Larsen, Torben.

In: IET Microwaves, Antennas & Propagation, Vol. 7, No. 14, 2013, p. 1161 - 1167.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - X-Parameter Based Modelling of Polar Modulated Power Amplifiers

AU - Wang, Yelin

AU - Nielsen, Troels Studsgaard

AU - Sira, Daniel

AU - Jensen, Ole Kiel

AU - Larsen, Torben

PY - 2013

Y1 - 2013

N2 - X-parameters are developed as an extension of S-parameters capable of modelling non-linear devices driven by large signals. They are suitable for devices having only radio frequency (RF) and DC ports. In a polar power amplifier (PA), phase and envelope of the input modulated signal are applied at separate ports and the envelope port is neither an RF nor a DC port. As a result, X-parameters may fail to characterise the effect of the envelope port excitation and consequently the polar PA. This study introduces a solution to the problem for a commercial polar PA. In this solution, the RF-phase path is modelled by X-parameters and the envelope path of the polar PA is simulated by a low-pass filter. The solution can be applied to a group of polar PAs who have the similar topology and design as the one in this work. Modulated signals with different channel bandwidths were applied to the model of the polar PA for simulations. The simulated error vector magnitude (EVM) and adjacent channel power ratio (ACPR) were compared with the measured data to validate the model. The maximum differences between the simulated and measured EVM and ACPR are less than 2% point and 3 dB, respectively.

AB - X-parameters are developed as an extension of S-parameters capable of modelling non-linear devices driven by large signals. They are suitable for devices having only radio frequency (RF) and DC ports. In a polar power amplifier (PA), phase and envelope of the input modulated signal are applied at separate ports and the envelope port is neither an RF nor a DC port. As a result, X-parameters may fail to characterise the effect of the envelope port excitation and consequently the polar PA. This study introduces a solution to the problem for a commercial polar PA. In this solution, the RF-phase path is modelled by X-parameters and the envelope path of the polar PA is simulated by a low-pass filter. The solution can be applied to a group of polar PAs who have the similar topology and design as the one in this work. Modulated signals with different channel bandwidths were applied to the model of the polar PA for simulations. The simulated error vector magnitude (EVM) and adjacent channel power ratio (ACPR) were compared with the measured data to validate the model. The maximum differences between the simulated and measured EVM and ACPR are less than 2% point and 3 dB, respectively.

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DO - 10.1049/iet-map.2012.0523

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JO - IET Microwaves, Antennas & Propagation

JF - IET Microwaves, Antennas & Propagation

SN - 1751-8725

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