DocumentCode :
843959
Title :
A Mixed-Signal Approach Towards Linear and Efficient N-Way Doherty Amplifiers
Author :
Neo, W. C Edmund ; Qureshi, Jawad ; Pelk, Marco J. ; Gajadharsing, John R. ; De Vreede, Leo C N
Author_Institution :
Delft Inst. of Microelectron. & Submicron Technol., Delft Univ. of Technol.
Volume :
55
Issue :
5
fYear :
2007
fDate :
5/1/2007 12:00:00 AM
Firstpage :
866
Lastpage :
879
Abstract :
A mixed-signal approach for the design and testing of high-performance N-way Doherty amplifiers is introduced. In support of this, an analysis of N-way power-combining networks is presented-in particular, their optimum design-by examining the relationship between the drive conditions of the active devices and input power. This analysis makes no prior assumption on the network topology and facilitates free-to-choose levels for the high-efficiency power back-off points. By comparing the results of this analysis with prior work, it is shown that very specific drive conditions apply to traditional three-way Doherty amplifier implementations to obtain simultaneously high-efficiency and high-linearity operation. To support these conclusions, a 15-W three-way Doherty amplifier was constructed using Philips GEN4 LDMOS devices featuring three separate inputs to independently drive the main and peaking devices. By testing this three-way amplifier with a custom-built measurement setup, capable of providing multiple digitally controlled coherent RF input signals with high spectral purity, a unique flexible amplifier concept is created resulting in a record-high efficiency for LDMOS-based Doherty amplifiers over a 12-dB back-off power range
Keywords :
MOS analogue integrated circuits; linearisation techniques; power amplifiers; 15 W; Philips GEN4 LDMOS devices; base station; digitally controlled coherent RF input signals; mixed-signal approach; power-combining network; three-way Doherty amplifier; Broadband amplifiers; High power amplifiers; Linearity; Multiaccess communication; Network topology; Operational amplifiers; Power amplifiers; Radio frequency; Radiofrequency amplifiers; Testing; Analysis; Doherty; base station; coherent signals; high efficiency; high power; linearity; mixed signal; power amplifier (PA);
fLanguage :
English
Journal_Title :
Microwave Theory and Techniques, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9480
Type :
jour
DOI :
10.1109/TMTT.2007.895160
Filename :
4195671
Link To Document :
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