Symmetric Three-Way Doherty Power Amplifier for High Efficiency and Linearity

This brief presents a three-way Doherty power amplifier (DPA) with a symmetric structure in terms of the output power capacities between the carrier and peaking amplifiers for high efficiency and linearity. Based on the analysis for the efficiency peak at the output power back-off, a symmetric structure was adopted to have higher overall efficiency for the modulated signal. Through the optimized bias condition for the two peaking amplifiers, the proposed three-way DPA can be linearized in the wide output power range. To validate the proposed scheme, a three-way DPA was designed and implemented using a 60 W GaN–HEMT for the carrier amplifier and two 30 W GaN–HEMTs for the peaking amplifiers. Using a 2.14 GHz long-term evolution downlink signal with a peak-to-average power ratio of 6.5 dB, the implemented symmetric three-way DPA exhibited a drain efficiency (DE) of 33.7% and an ACLR of −38 dBc at an average output power of 41.4 dBm. Compared to the condition with the same bias for the peaking amplifiers, the DE and average output power were improved by 8.0% and 2.4 dB for the given ACLR of −38 dBc, respectively.

[1]  A 400 W 2-way asymmetrical doherty PA with 50% efficiency based on second-generation airfastTM LDMOS technology , 2015, 2015 IEEE Topical Conference on Power Amplifiers for Wireless and Radio Applications (PAWR).

[2]  Bumjae Shin,et al.  A fully matched N-way Doherty amplifier with optimized linearity , 2003 .

[3]  Slim Boumaiza,et al.  Electronically Tunable Doherty Power Amplifier for Multi-Mode Multi-Band Base Stations , 2014, IEEE Transactions on Circuits and Systems I: Regular Papers.

[4]  Cheon-seok Park,et al.  A New Compact Load Network for Doherty Amplifiers Using an Imperfect Quarter-Wave Line , 2007, IEEE Transactions on Microwave Theory and Techniques.

[5]  Fadhel M. Ghannouchi,et al.  Design for linearizability of GaN based multi-carrier Doherty power amplifier through bias optimization , 2012, 2012 19th IEEE International Conference on Electronics, Circuits, and Systems (ICECS 2012).

[6]  Mun-Woo Lee,et al.  A highly efficient and linear inverted Doherty power amplifier with unsymmetrical delay path , 2011 .

[7]  Jangheon Kim,et al.  The Doherty power amplifier , 2006, IEEE Microwave Magazine.

[8]  P. Handel,et al.  Performance Evaluation of Peak-to-Average Power Ratio Reduction and Digital Pre-Distortion for OFDM Based Systems , 2011, IEEE Transactions on Microwave Theory and Techniques.

[9]  Sang-Hyun Chun,et al.  Inverted asymmetric Doherty power amplifier driven by two-stage symmetric Doherty amplifier , 2010 .

[10]  Cuiping Yu,et al.  Design of Linearity Improved Asymmetrical GaN Doherty Power Amplifier Using Composite Right/Left-Handed Transmission Lines , 2013 .

[11]  Mincheol Seo,et al.  Broadband Doherty Power Amplifier Based on Asymmetric Load Matching Networks , 2015, IEEE Transactions on Circuits and Systems II: Express Briefs.

[12]  Fadhel M. Ghannouchi,et al.  Compensating I–Q Imperfections in Hybrid RF/Digital Predistortion With an Adapted Lookup Table Implemented in an FPGA , 2010, IEEE Transactions on Circuits and Systems II: Express Briefs.

[13]  Mun-Woo Lee,et al.  A highly linear and efficient three-way Doherty amplifier using two-stage GaN HEMT cells for repeater systems , 2009 .

[14]  Mun-Woo Lee,et al.  Linearity improvement of three‐way Doherty amplifier using power tracking bias supply method , 2008 .

[15]  Fadhel M. Ghannouchi,et al.  RF/DSP Codesign Methodology of Enhanced Doherty Amplifiers , 2012, IEEE Transactions on Circuits and Systems II: Express Briefs.