A High Efficiency WCDMA RF Power Amplifier With Adaptive, Dual-Mode Buck-Boost Supply and Bias-Current Control

Radio-frequency (RF) power amplifiers (PAs) are often the most power-consuming blocks in portable wireless systems, and maintaining high PA efficiency at heavy and light loads is therefore critical for extended battery life. This letter presents how a 0.5-mum CMOS dynamically adaptive, dual-mode buck-boost power supply and bias-current control circuit improves PA efficiency. The proposed system is validated with a 1.96-GHz, 25-dBm SiGe heterojunction bipolar transistor (HBT) wideband code division multiple access RF PA, where its supply voltage and bias current are dynamically adjusted from 0.4 to 4.5 V and 25 to 220mA, respectively, over an output power range of -50 to 25dBm. The prototype system is functional for a 1.8-4.2V input supply range, meeting adjacent- and alternate-channel leakage ratio specifications with less than 10% of error vector magnitude across the entire power range. The average efficiency of the dynamically adaptive system (13.67%) was 7times better than the corresponding fixed-supplied, fixed-biased scheme (1.95%), with the same HBT PA