Hostname: page-component-848d4c4894-2pzkn Total loading time: 0 Render date: 2024-05-25T02:41:10.369Z Has data issue: false hasContentIssue false

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

Published online by Cambridge University Press:  11 February 2016

Rocco Giofrè*
Affiliation:
Electronic Engineering Department, University of Roma Tor Vergata, 00133 Roma, Italy. Phone: +39 06 7259 7346
Paolo Colantonio
Affiliation:
Electronic Engineering Department, University of Roma Tor Vergata, 00133 Roma, Italy. Phone: +39 06 7259 7346
Franco Giannini
Affiliation:
Electronic Engineering Department, University of Roma Tor Vergata, 00133 Roma, Italy. Phone: +39 06 7259 7346
Chiara Ramella
Affiliation:
Electronic Engineering Department, University of Roma Tor Vergata, 00133 Roma, Italy. Phone: +39 06 7259 7346
Vittorio Camarchia
Affiliation:
Electronics and Telecommunications Department, Politecnico di Torino, 10129 Torino, Italy
Mustazar Iqbal
Affiliation:
Electronics and Telecommunications Department, Politecnico di Torino, 10129 Torino, Italy
Marco Pirola
Affiliation:
Electronics and Telecommunications Department, Politecnico di Torino, 10129 Torino, Italy
Roberto Quaglia
Affiliation:
Electronics and Telecommunications Department, Politecnico di Torino, 10129 Torino, Italy School of Engineering, Cardiff University, Cardiff, CF24 3AA, UK
*
Corresponding author:R. Giofrè Email: giofr@ing.uniroma2.it

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.

Type
Research Papers
Copyright
Copyright © Cambridge University Press and the European Microwave Association 2016 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

[1] Bhushan, N. et al. : Network densification: the dominant theme for wireless evolution into 5G. IEEE Commun. Mag., 52 (2) (2014), 8289.CrossRefGoogle Scholar
[2] Colantonio, P.; Giannini, F.; Limiti, E.: High Efficiency RF and Microwave Solid State Power Amplifiers, ser. Microwave and Optical Engineering, John Wiley & Sons, Chichester, UK, 2009.CrossRefGoogle Scholar
[3] Kenington, P.: High linearity RF amplifier design, ser. Artech House Microwave Library, Artech House, Norwood, MA, 2000.Google Scholar
[4] Camarchia, V.; Pirola, M.; Quaglia, R.; Jee, S.; Cho, Y.; Kim, B.: The Doherty power amplifier: review of recent solutions and trends. IEEE Trans. Microw. Theory Tech., 63 (2) (2015), 559571.Google Scholar
[5] Kim, B.; Moon, J.; Kim, I.: Efficiently amplified. IEEE Microw. Mag., 11 (5) (2010), 87100.Google Scholar
[6] Ghannouchi, F.M.; Hammi, O.: Behavioral modeling and predistortion. IEEE Microw. Mag., 10 (7) (2010), 5264.CrossRefGoogle Scholar
[7] Little, S.: Is microwave backhaul up to the 4 G task. IEEE Microw. Mag., 10 (5) (2009), 6774.Google Scholar
[8] Camarchia, V. et al. : Fabrication and nonlinear characterization of GaN HEMTs on SiC and sapphire for high-power applications. Int. J. RF Microw. Comp. Aided Eng., 16 (1) (2006), 7080.Google Scholar
[9] Reveyrand, T. et al. : GaN transistor characterization and modeling activities performed within the frame of the KorriGaN project. Int. J. Microw. Wireless Technol., 2 (1) (2010), 5161.Google Scholar
[10] Camarchia, V. et al. : High-efficiency 7 GHz Doherty GaN MMIC power amplifiers for microwave backhaul radio links. IEEE Trans. Electron Devices, 60 (10) (2013), 35923595.CrossRefGoogle Scholar
[11] Kistchinsky, A.: GaN solid-state microwave power amplifiers – State-of-the-art and future trends, in Proc. IEEE Crimean Microw. Telecom. Tech. CriMiCo, 14–18 September 2009, 11–16.Google Scholar
[12]Harmonized European Standard ETSI EN 302 217-2-2. “Fixed Radio Systems; Characteristics and requirements for point-to-point equipment and antennas; Part 2-2: Digital systems operating in frequency bands where frequency co-ordination is applied,” April 2014. Available at www.etsi.org, ref. REN/ATTM-04025.Google Scholar
[13]European Standard ETSI EN 302 217-2-1. “Fixed Radio Systems; Characteristics and requirements for point-to-point equipment and antennas; Part 2-1: System dependent requirements for digital systems operating in frequency bands where frequency co-ordination is applied,” December 2014. Available at www.etsi.org, ref. REN/ATTM-04017.Google Scholar
[14] Giofré, R. et al. : GaN MMICs for microwave backhaul: Doherty vs. combined class-AB power amplifier, in Proc. of European Microwave Conf. (EuMiC), Paris, France, 2015.Google Scholar
[15] Giofré, R.; Piazzon, L.; Colantonio, P.; Giannini, F.: A closed-form design technique for ultra-wideband Doherty power amplifiers. IEEE Trans. Microw. Theory Tech., 62 (12) (2014), 34143424.Google Scholar
[16] Shelton, J.; Mosko, J.A.: Synthesis and design of wide-band equal-ripple TEM directional couplers and fixed phase shifters. IEEE Trans. Microw. Theory Tech., 14 (10) (1966), 462473.CrossRefGoogle Scholar
[17] Piazzon, L. et al. : Effect of load modulation on phase distortion in Doherty Power Amplifiers. IEEE Microw. Wireless Compon. Lett., 24 (7) (2014), 505507.Google Scholar
[18] Quaglia, R.; Tao, J.; Vittorio, C.: Frequency extension of system level characterization and predistortion setup for on-wafer microwave power amplifiers, in Proc. of European Microwave Conf. (EuMiC), Rome, 6–7 October 2014, 488491.CrossRefGoogle Scholar
[19] Behtash, R. et al. : Coplanar AlGaN/GaN HEMT power amplifier MMIC at X-band, in 2004 IEEE MTT-S Int. Microwave Symp. Digest, vol. 3, June 2004, 16571659.Google Scholar
[20] Klockenhoff, H.; Behtash, R.; Wurfl, J.; Heinrich, W.; Trankle, G.: A compact 16 Watt X-Band GaN-MMIC power amplifier, in IEEE MTT-S Int. Microw. Symp. Digest, June 2006, 18461849.Google Scholar
[21] Quaglia, R.; Camarchia, V.; Pirola, M.; Moreno Rubio, J.; Ghione, G.: Linear GaN MMIC combined power amplifiers for 7-GHz microwave backhaul. IEEE Trans. Microw. Theory Tech. 62 (11) (2014), 27002710.Google Scholar
[22] Gustafsson, D.; Andersson, C.; Fager, C.: A GaN MMIC modified Doherty power amplifier with large bandwidth and reconfigurable efficiency. IEEE Trans. Microw. Theory Tech. 62 (12) (2014), 30063016.CrossRefGoogle Scholar
[23] Colantonio, P.; Giannini, F.; Giofré, R.; Limiti, E.; Piazzon, L.: An X-Band GaAs MMIC Doherty Power Amplifier, Workshop on Integrated Nonlinear Microwave and Millimeter-Wave Circuits (INMMIC), 2010, April 2010, 4144.CrossRefGoogle Scholar
[24] Gustafsson, D.; Cahuana, J.C.; Kuylenstierna, D.; Angelov, I.; Rorsman, N.; Fager, C.: A wideband and compact GaN MMIC Doherty amplifier for microwave link applications. IEEE Trans. Microw. Theory Tech., 61 (2) (2013), 922930.Google Scholar
[25] Camarchia, V.; Fang, J.; Moreno Rubio, J.; Pirola, M.; Quaglia, R.: 7 GHz MMIC GaN Doherty power amplifier with 47% efficiency at 7 dB output back-off. IEEE Microw. Wireless Compon. Lett., 23 (1) (2013), 3436.Google Scholar
[26] Piazzon, L.; Colantonio, P.; Giannini, F.; Giofré, R.: 15% Bandwidth 7 GHz GaN-MMIC Doherty amplifier with enhanced auxiliary chain. Microw. Opt. Technol. Lett., Wiley, 56 (2) (2014), 502504.CrossRefGoogle Scholar