Title :
Linearity improvement in RF power amplifier system using integrated Auxiliary Envelope Tracking system
Author :
Yusoff, Z. ; Lees, J. ; Benedikt, J. ; Tasker, P.J. ; Cripps, S.C.
Author_Institution :
Centre for High Freq. Eng., Cardiff Univ., Cardiff, UK
Abstract :
A new technique called Auxiliary Envelope Tracking (AET) is proposed, which demonstrates substantial improvement in linearity of RF power amplifiers. A small amplitude envelope-tracking voltage is superimposed on the fixed DC bias of a specially designed 25W GaN HEMT Class AB RF power amplifier (RFPA). A large improvement in third-order intermodulation (IM3) distortion has been observed while maintaining low fifth-order intermodulation (IM5). The overall drain efficiency of the RFPA is also observed to improve, even when the power consumption of the envelope tracking generator is included. The AET concept uses a simple and easily integrated system that consists of an RFPA, a diplexer and an envelope amplifier.
Keywords :
high electron mobility transistors; power amplifiers; HEMT class AB RF power amplifier; RF power amplifier system; amplitude envelope tracking voltage; auxiliary envelope tracking system; diplexer; envelope amplifier; envelope tracking generator; fifth-order intermodulation; fixed DC bias; linearity improvement; power 25 W; power consumption; third-order intermodulation distortion; Gallium nitride; HEMTs; Impedance; Linearity; Power amplifiers; Radio frequency; Voltage measurement; Gallium nitride (GaN); Intermodulation; Linearization techniques; Power amplifiers;
Conference_Titel :
Microwave Symposium Digest (MTT), 2011 IEEE MTT-S International
Conference_Location :
Baltimore, MD
Print_ISBN :
978-1-61284-754-2
Electronic_ISBN :
0149-645X
DOI :
10.1109/MWSYM.2011.5972769
