Summary: IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 53, NO. 2, FEBRUARY 2005 529
A High Average-Efficiency SiGe HBT Power
Amplifier for WCDMA Handset Applications
Junxiong Deng, Student Member, IEEE, Prasad S. Gudem, Member, IEEE, Lawrence E. Larson, Fellow, IEEE, and
Peter M. Asbeck, Fellow, IEEE
Abstract--The linearity of a silicon­germanium (SiGe) HBT
power amplifier (PA) is analyzed with the help of a power-de-
pendent 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 5- and 10-MHz
offsets at 23.9-dBm average channel output power are 33 and
58.8 dBc, respectively, and satisfies the Third-Generation Part-
nership Project WCDMA specifications. The output power at the
1-dB compression point is 25.9 dBm.
Index Terms--Average power efficiency, dynamic biasing,

Source: Asbeck, Peter M. - Department of Electrical and Computer Engineering, University of California at San Diego
Larson, Larry - Department of Electrical and Computer Engineering, University of California at San Diego

Collections: Engineering