DocumentCode :
1468545
Title :
RF/DSP Codesign Methodology of Enhanced Doherty Amplifiers
Author :
Darraji, Ramzi ; Ghannouchi, Fadhel M.
Author_Institution :
Dept. of Electr. & Comput. Eng., Univ. of Calgary, Calgary, AB, Canada
Volume :
59
Issue :
4
fYear :
2012
fDate :
4/1/2012 12:00:00 AM
Firstpage :
219
Lastpage :
223
Abstract :
In this brief, a mixed radio frequency/digital signal processing (DSP) codesign approach is proposed to enhance the performance of Doherty power amplifiers (PAs). For the hardware optimization, a load-pull-based design methodology is proposed to determine the optimal matching elements of the main amplifier for enhanced efficiency at back-off. Subsequently, DSP control of the baseband input signal is used to efficiently distribute the drive power between the main and auxiliary amplifiers in order to enhance the efficiency at high power levels and also to improve the linearity. Precisely, the input power is evenly distributed between the two amplifiers at the back-off region and then unequally split with more drive into the auxiliary amplifier once the latter turns on. This allows for improving the load modulation behavior of the Doherty PA and flattening its gain response, which yield enhanced efficiency and improved linearity. For the experimental validation, the proposed codesign approach is applied to implement a dual-input Doherty PA based on a 10-W gallium nitride (GaN) device. Measurement results with wideband code division multiple access demonstrated improvements of up to 5% in average drain efficiency and up to 3 dB in adjacent channel leakage ratio.
Keywords :
III-V semiconductors; UHF power amplifiers; digital signal processing chips; gallium compounds; network synthesis; wide band gap semiconductors; DSP control; GaN; RF/DSP codesign method; baseband input signal; dual input Doherty power amplifier; enhanced Doherty amplifiers; frequency 2.14 GHz; hardware optimization; load modulation; load-pull-based design methodology; mixed radio frequency-digital signal processing; optimal matching elements; power 10 W; Digital signal processing; Impedance; Linearity; Multiaccess communication; Optimization; Power distribution; Radio frequency; Digital adaptive power distribution; Doherty amplifier; efficiency; linearity; wideband code division multiple access (WCDMA);
fLanguage :
English
Journal_Title :
Circuits and Systems II: Express Briefs, IEEE Transactions on
Publisher :
ieee
ISSN :
1549-7747
Type :
jour
DOI :
10.1109/TCSII.2012.2188455
Filename :
6168797
Link To Document :
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