High-efficiency L-band Kahn-technique transmitter

Author

Raab, F.H. ; Sigmon, B.E. ; Myers, R.G. ; Jackson, R.M.

Author_Institution

Green Mountain Radio Res., Colchester, VT, USA

Volume

2

fYear

1998

fDate

7-12 June 1998

Firstpage

585

Abstract

This paper describes a 20 W PEP linear L-band transmitter based upon the Kahn envelope-elimination-and-restoration technique. A double envelope-feedback loop assures high linearity. The RF power amplifier employs a two stage MMIC driver amplifier and a 20 W PA biased for class-AB operation. The class-S modulator includes a high speed comparator and 0.5 /spl mu/m HFETs in its output stage. A double envelope-feedback loop assures both high linearity and time-delay equalization for RF bandwidths to 150 kHz. With a two-tone signal the transmitter achieves an efficiency of 56% at full power (40 dBm under QPSK modulation), and 35% at 18 dB in back-off. The third-order IMDs for a two-tone signal vary from -30 dBc to -40 dBc over a 20 dB back-off range.

Keywords

radio transmitters; 0.5 micron; 150 kHz; 20 W; 35 to 56 percent; HFET output stage; Kahn-technique transmitter; PEP linear L-band transmitter; QPSK modulation; RF power amplifier; UHF; class-AB operation; class-S modulator; double envelope-feedback loop; envelope-elimination/restoration technique; high linearity; high speed comparator; high-efficiency transmitter; third-order IMD; time-delay equalization; two stage MMIC driver amplifier; Driver circuits; HEMTs; L-band; Linearity; MMICs; Operational amplifiers; Power amplifiers; Radio frequency; Radiofrequency amplifiers; Transmitters;

fLanguage

English

Publisher

ieee

Conference_Titel

Microwave Symposium Digest, 1998 IEEE MTT-S International

Conference_Location

Baltimore, MD, USA

ISSN

0149-645X

Print_ISBN

0-7803-4471-5

Type

conf

DOI

10.1109/MWSYM.1998.705061

Filename

705061