DocumentCode :
1517938
Title :
A high-efficiency RF transmitter using VCO-derived synthesis: CALLUM
Author :
Jennings, David J. ; McGeehan, Joseph P.
Author_Institution :
Centre for Commun. Res., Bristol Univ., UK
Volume :
47
Issue :
6
fYear :
1999
fDate :
6/1/1999 12:00:00 AM
Firstpage :
715
Lastpage :
721
Abstract :
The combined analog locked-loop universal modulator (CALLUM) is a radio-frequency (RF) transmitter topology which produces a linear output through the use of nonlinear, but highly efficient, RF power amplifiers. This is achieved through careful phasing of two constant-envelope vectors, each derived from voltage-controlled oscillators. The system up-converts and amplifies a baseband signal within a closed-loop feedback scheme. The optimal CALLUM system requires complex baseband processing, but a simplified version, known as CALLUM2, can be implemented using simple analog circuitry. This paper provides some insight into the behavior of such systems and gives results from an experimental CALLUM2 system in response to a modulating signal compatible with that used in the terrestrial trunked radio standard
Keywords :
feedback amplifiers; mobile radio; modulators; phase locked loops; power amplifiers; radio transmitters; radiofrequency amplifiers; telecommunication standards; CALLUM; CALLUM2; RF power amplifiers; VCO-derived synthesis; baseband signal; closed-loop feedback scheme; combined analog locked-loop universal modulator; complex baseband processing; constant-envelope vectors; high-efficiency RF transmitter; linear output; mobile radio; modulating signal; terrestrial trunked radio standard; Baseband; Circuits; Feedback; High power amplifiers; Radio frequency; Radio transmitters; Radiofrequency amplifiers; Topology; Vectors; Voltage-controlled oscillators;
fLanguage :
English
Journal_Title :
Microwave Theory and Techniques, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9480
Type :
jour
DOI :
10.1109/22.769341
Filename :
769341
Link To Document :
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