Title :
On the Optimization of Biasing Conditions in a Digitally-Linearized Power Amplifier
Author :
Safari, Nima ; Olavsbråten, Morten ; Røste, Terje
Author_Institution :
Dept. of Electron. & Telecommun., NTNU, Trondheim
Abstract :
Changing the class of operation in a power amplifier (PA) affects the linearity and the efficiency of the PA. In this paper, the linearization performance and the efficiency enhancement of a Digital Predistorter (DPD) in a transmitter is evaluated with different PA classes. The digital predistorter is implemented in real-time on a Digital Signal Processor (DSP). The PA under test is a 2-stage 2-watt amplifier used in mobile terminals in Inmarsat Broadband Global Area Network (BGAN) systems. The gate bias of the PA is tunable for changing the biasing conditions. It is shown that by driving the PA into class B, we increase the memory effects and therefore reduce the effectiveness of memoryless predistortion. It was also shown that using a memoryless digital predistorter and a PA biased near class AB operation, an efficiency of about 41% is achievable while the BGAN system requirements are met.
Keywords :
digital signal processing chips; linearisation techniques; mobile communication; power amplifiers; Inmarsat Broadband Global Area Network; class B power amplifier; digital predistorter; digital signal processor; digitally linearized power amplifier; linearization performance; mobile terminals; power 2 W; Baseband; Digital signal processing; Linearity; Microwave amplifiers; Operational amplifiers; Peak to average power ratio; Power amplifiers; Predistortion; Quadrature amplitude modulation; Transmitters;
Conference_Titel :
Microwave Conference, 2008. EuMC 2008. 38th European
Conference_Location :
Amsterdam
Print_ISBN :
978-2-87487-006-4
DOI :
10.1109/EUMC.2008.4751515