A combined class-AB and a Doherty power amplifier conceived for microwave backhaul in the 7 GHz frequency band are here presented and compared. They are fabricated in the same GaN monolithic process and have identical total active device periphery. For the given application, the linearity-efficiency trade-off for the two architectures is discussed. The two modules have been thoroughly characterized in linear and non-linear continuous wave conditions. Then, to evaluate linearity under the actual operative conditions, a system level characterization has been carried out, applying a modulated input signal and comparing the spectral responses of the two amplifiers with and without digital predistortion. A saturated output power of 40 dBm has been achieved by both circuits. At 6 dB of output back-off, the Doherty amplifier shows an efficiency of 33%, 10 points higher than that of the class-AB module. On the other hand, system level measurements show that, adopting the same predistorter complexity to comply with the reference standard emission masks, the Doherty amplifier needs at least 1 dB of extra back-off. This negatively affects its efficiency, therefore reducing the advantages it can claim with respect to the class-AB amplifier in continuous wave condition.

Giofrè, R., Colantonio, P., Giannini, F., Ramella, C., Camarchia, V., Iqbal, M., et al. (2016). A comprehensive comparison between GaN MMIC Doherty and combined class-AB power amplifiers for microwave radio links. INTERNATIONAL JOURNAL OF MICROWAVE AND WIRELESS TECHNOLOGIES, 1-9 [10.1017/S175907871600012X].

A comprehensive comparison between GaN MMIC Doherty and combined class-AB power amplifiers for microwave radio links

GIOFRE', ROCCO;COLANTONIO, PAOLO;GIANNINI, FRANCO;
2016-03

Abstract

A combined class-AB and a Doherty power amplifier conceived for microwave backhaul in the 7 GHz frequency band are here presented and compared. They are fabricated in the same GaN monolithic process and have identical total active device periphery. For the given application, the linearity-efficiency trade-off for the two architectures is discussed. The two modules have been thoroughly characterized in linear and non-linear continuous wave conditions. Then, to evaluate linearity under the actual operative conditions, a system level characterization has been carried out, applying a modulated input signal and comparing the spectral responses of the two amplifiers with and without digital predistortion. A saturated output power of 40 dBm has been achieved by both circuits. At 6 dB of output back-off, the Doherty amplifier shows an efficiency of 33%, 10 points higher than that of the class-AB module. On the other hand, system level measurements show that, adopting the same predistorter complexity to comply with the reference standard emission masks, the Doherty amplifier needs at least 1 dB of extra back-off. This negatively affects its efficiency, therefore reducing the advantages it can claim with respect to the class-AB amplifier in continuous wave condition.
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore ING-INF/01 - Elettronica
English
Circuit design and applications; Power amplifiers and linearizers; Electrical and Electronic Engineering
http://journals.cambridge.org/action/displayJournal?jid=MRF
Giofrè, R., Colantonio, P., Giannini, F., Ramella, C., Camarchia, V., Iqbal, M., et al. (2016). A comprehensive comparison between GaN MMIC Doherty and combined class-AB power amplifiers for microwave radio links. INTERNATIONAL JOURNAL OF MICROWAVE AND WIRELESS TECHNOLOGIES, 1-9 [10.1017/S175907871600012X].
Giofre', R; Colantonio, P; Giannini, F; Ramella, C; Camarchia, V; Iqbal, M; Pirola, M; Quaglia, R
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2108/142847
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