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A 1-3-GHz Digitally Controlled Dual-RF Input Power-Amplifier Design Based on a Doherty-Outphasing Continuum Analysis

Christer Andersson (Institutionen för mikroteknologi och nanovetenskap, Mikrovågselektronik) ; David Gustafsson (Institutionen för mikroteknologi och nanovetenskap, Mikrovågselektronik) ; Jessica Chani Cahuana (Institutionen för signaler och system, Kommunikationssystem) ; Richard Hellberg ; Christian Fager (Institutionen för mikroteknologi och nanovetenskap, Mikrovågselektronik)
IEEE Transactions on Microwave Theory and Techniques (0018-9480). Vol. 61 (2013), 10, p. 3743-3752.
[Artikel, refereegranskad vetenskaplig]

This paper presents a linear multi-harmonic analysis method to evaluate the performance of digitally controlled dual RF-input power amplifiers (PAs). The method enables, due to its low computational cost, optimization of PA efficiency and bandwidth in a complex design space involving two independent inputs. Under the idealized assumption of short-circuited higher harmonics, the analysis is used to prove the existence of a Doherty-outphasing continuum, featuring high average efficiency over 100% fractional bandwidth. With this result as a foundation, a combiner incorporating microwave transistor parasitics is analyzed without assuming short-circuited higher harmonics, showing that high average efficiencies are also achievable under more realistic conditions. A PA is straightforwardly designed from these calculation results using two 15-W GaN HEMTs. The simulated layout-ready (large-signal transistor model) PA average drain efficiency exceeds 50% over 1.1-3.7 GHz for a 6.7-dB peak-to-average power-ratio WCDMA signal. The measured PA has a maximum output power of 44 +/- 0.9 dBm and a 6-dB output power back-off (OPBO) power-added efficiency (PAE) of 45% over 1-3 GHz. After applying digital pre-distortion, excellent linearity is demonstrated when transmitting the WCDMA signal, resulting in an adjacent channel leakage power ratio lower than -57 dBc with corresponding average PAE of 50% and 40% at 1.2 and 2.3 GHz, respectively. This is, to the authors' knowledge, the most wideband OPBO efficiency enhanced PA reported to date, proving the effectiveness of employing linear multi-harmonic analysis in dual-input PA design.

Nyckelord: Chireix; Doherty; energy efficiency; gallium-nitride (GaN); outphasing; power amplifiers (PAs)



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Denna post skapades 2013-11-12. Senast ändrad 2015-12-17.
CPL Pubid: 186461

 

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