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AlGaN/GaN-based power amplifiers for mobile radio applications: A review from the system supplier's perspective

: Wiegner, D.; Luz, G.; Jüschke, P.; Machinal, R.; Merk, T.; Seyfried, U.; Templ, W.; Pascht, A.; Quay, R.; Raay, F. van


International journal of microwave and wireless technologies 2 (2010), No.1, pp.95-104
ISSN: 1759-0795
ISSN: 1759-0787
Journal Article
Fraunhofer IAF ()
AlGaN/GaN HEMT; W-CDMA; power amplifier; Multiband; Doherty; envelope tracking; drain efficiency; digital predistortion

This paper gives a summarized overview on the progress and achievements on AlGaN/GaN high electron mobility transistors (HEMT)-based power amplifiers (PAs) for mobile radio applications which have been achieved within two national funded German projects during a period of six years. Starting with a first 34 dBm (2.5 W, peak) amplifier in 2003 the impressive progress toward highly efficient S-band mobile radio PAs with up to .50 dBm (100 W) peak output power is described by means of some selected single- and multiband amplifier demonstrators. This progress has been mainly enabled by clear progress on GaN technology, device packaging, and PA design. Targeting at highly efficient single-band amplifier applications, a 2.7 GHz symmetrical Doherty amplifier with up to 45% drain efficiency at close to 45 dBm average output power under single-carrier W-CDMA (Wideband Code Division Multiple Access) operation using digital predistortion can be highlighted. In case of multiband capable amplifiers addressing software-defined radio applications, a class-AB-based demonstrator covering a frequency range from 1.8 to 2.7 GHz was realized. The amplifier showed .30% drain efficiency up to 2.5 GHz as well as up to 40 dBm average output power under single-carrier W-CDMA operation using proprietary digital predistortion. Finally, Alcatel-Lucent's activities on envelope tracking for future efficiency improved GaN-based amplifiers are described.