Title :
A class-J power amplifier with varactor-based dynamic load modulation across a large bandwidth
Author :
Hallberg, William ; Gustafsson, David ; Ozen, Mustafa ; Andersson, Christer M. ; Kuylenstierna, Dan ; Fager, Christian
Author_Institution :
Chalmers Univ. of Technol., Gothenburg, Sweden
Abstract :
A novel class-J operated power amplifier (PA) utilizing varactor-based dynamic load modulation is presented. It is theoretically shown that the proposed PA can maintain high average efficiency across more than 35% RF bandwidth by means of a purely reactive load modulation after the transistor output capacitance. The theory is experimentally verified by a 15 W GaN HEMT PA operating from 1.80 to 2.20 GHz, using SiC varactors as dynamically tunable load elements. In the band, the PA presents a power added efficiency (PAE) higher than 39% at 6 dB output power back-off. For a 3.84 MHz W-CDMA signal with 6.7 dB peak to average power ratio, an average PAE higher than 39% and an adjacent channel leakage ratio below -45.8 dBc are obtained across the entire band after linearization.
Keywords :
III-V semiconductors; UHF power amplifiers; code division multiple access; gallium compounds; high electron mobility transistors; silicon compounds; varactors; wide band gap semiconductors; GaN; GaN HEMT power amplifier; SiC; SiC varactors; W-CDMA signal; class-J operated power amplifier; frequency 1.80 GHz to 2.20 GHz; frequency 3.84 MHz; power 15 W; reactive load modulation; transistor output capacitance; varactor-based dynamic load modulation; Bandwidth; Gallium nitride; HEMTs; Multiaccess communication; Peak to average power ratio; Radio frequency; Spread spectrum communication; Energy efficiency; gallium nitride (GaN); power amplifiers; silicon carbide (SiC); varactors; wideband;
Conference_Titel :
Microwave Symposium (IMS), 2015 IEEE MTT-S International
Conference_Location :
Phoenix, AZ
DOI :
10.1109/MWSYM.2015.7166734
