Title :
A high average-efficiency SiGe HBT power amplifier for WCDMA handset applications
Author :
Deng, Junxiong ; Gudem, Prasad S. ; Larson, Lawrence E. ; Asbeck, Peter M.
Author_Institution :
Dept. of Electr. & Comput. Eng., Univ. of California, La Jolla, CA
Abstract :
The linearity of a silicon-germanium (SiGe) HBT power amplifier (PA) is analyzed with the help of a power-dependent coefficient Volterra technique. The effect of emitter inductance is included and the dominant sources of nonlinearity are identified. A dynamic current biasing technique is developed to improve the average power efficiency for wide-band code-division multiple-access (WCDMA) PAs. The average power efficiency is improved by more than a factor of two compared to a typical class-AB operation, while the power gain keeps roughly constant. The measured adjacent channel power ratio with 5and 10-MHz offsets at 23.9-dBm average channel output power are -33 and -58.8 dBc, respectively, and satisfies the Third-generation partnership project WCDMA specifications. The output power at the 1-dB compression point is 25.9 dBm
Keywords :
3G mobile communication; Ge-Si alloys; Volterra series; code division multiple access; equivalent circuits; heterojunction bipolar transistors; inductance; intermodulation distortion; mobile handsets; power amplifiers; power bipolar transistors; semiconductor device models; wideband amplifiers; -33 dB; -58.8 dB; 1 dB; 10 MHz; 23.9 dB; 25.9 dB; 5 MHz; CDMA; HBT emitter inductance; SiGe; SiGe HBT power amplifier; adjacent channel power ratio; average channel output power; average power efficiency; class-AB operation; constant power gain; dynamic current biasing method; emitter inductance effect; equivalent circuits; heterojunction bipolar transistor; intermodulation distortion; power dependent coefficient Volterra method; third generation partnership project; wideband CDMA handset applications; wideband code division multiple access; Broadband amplifiers; Germanium silicon alloys; Heterojunction bipolar transistors; High power amplifiers; Linearity; Multiaccess communication; Power amplifiers; Power generation; Silicon germanium; Telephone sets; Average power efficiency; HBTs; Volterra series; dynamic biasing; intermodulation distortion; linearity; power amplifiers (PAs); wide-band code division multiple access (WCDMA);
Journal_Title :
Microwave Theory and Techniques, IEEE Transactions on
DOI :
10.1109/TMTT.2004.840629
