Title :
A 2.655 GHz 3-stage Doherty power amplifier using envelope tracking technique
Author :
Kim, Ildu ; Kim, Bumman
Author_Institution :
Dept. of Electr. Eng., Pohang Univ. of Sci. & Technol.(POSTECH), Pohang, South Korea
Abstract :
We demonstrates an optimized design of a highly efficient 3-stage Doherty PA for the 802.16e Mobile world interoperability for microwave access(WiMAX) application at 2.655-GHz. The `3-stage´ Doherty PA is the most efficient architecture among the various Doherty PAs for a high peak to average power ratio(PAPR) signal. However, due to the low quiescent bias point of the peaking PA, it has an improper load modulation problem, which causes over saturated operation of the carrier PA and insufficient peak power. We have solved the problem using a gate envelope tracking(ET) technique. Using the ADS and Matlab simulations, the behavior of the 3-stage Doherty PA employing the ET technique is presented. For the WiMAX signal with a 7.8 ~ 8.5 dB PAPR and 20-MHz instantaneous bandwidth, the measured efficiency of the proposed 3-stage Doherty PA has been maintained 56.7% at an average output power of 43.3 dBm, a 7.2 dB backed-off output power from peak output power level. These experimental results clearly show that the 3-stage Doherty with ET technique has a superior efficiency with high peak power. The PAs accompanied with the DPD are very good candidates for the highly efficient and linear base-station transmitter.
Keywords :
UHF power amplifiers; WiMax; telecommunication standards; transmitters; 3-stage Doherty power amplifier; ADS simulation; IEEE 802.16e; Matlab simulation; WiMAX; bandwidth 20 MHz; envelope tracking; frequency 2.655 GHz; linear base-station transmitter; load modulation; peak to average power ratio; quiescent bias point; saturated operation; world interoperability for microwave access; Bandwidth; Design optimization; Linearity; Linearization techniques; Peak to average power ratio; Power amplifiers; Power generation; Power measurement; Transmitters; WiMAX;
Conference_Titel :
Microwave Symposium Digest (MTT), 2010 IEEE MTT-S International
Conference_Location :
Anaheim, CA
Print_ISBN :
978-1-4244-6056-4
Electronic_ISBN :
0149-645X
DOI :
10.1109/MWSYM.2010.5517777