Design for linearizability of GaN based multi-carrier Doherty power amplifier through bias optimization

In this paper, a GaN based symmetrical Doherty power amplifier is designed. The Doherty amplifier bias conditions are optimized for a trade-off between power added efficiency and linearity. The carrier amplifier is biased for linearity and the peaking amplifier bias is chosen for maximum power added efficiency. Measurement results under a four carrier WCDMA drive signal show respectively 43% power added efficiency and -32.5dBc adjacent channel leakage ratio at 6dB output power back-off. Linearization of the designed Doherty PA using baseband digital predistortion led to quasi perfect cancellation of spectrum regrowth while operating at an output power back-off equal to the input signal's peak to average power ratio.

[1]  Yi-Jan Emery Chen,et al.  Impact of bias schemes on Doherty power amplifiers , 2005, 2005 IEEE International Symposium on Circuits and Systems.

[2]  M. Berroth,et al.  A microwave Doherty amplifier with programmable bias control , 2008, 2008 51st Midwest Symposium on Circuits and Systems.

[3]  F.M. Ghannouchi,et al.  Synergetic Crest Factor Reduction and Baseband Digital Predistortion for Adaptive 3G Doherty Power Amplifier Linearizer Design , 2008, IEEE Transactions on Microwave Theory and Techniques.

[4]  F.M. Ghannouchi,et al.  Behavioral modeling and predistortion , 2009, IEEE Microwave Magazine.

[5]  Taijun Liu,et al.  Systematic and Adaptive Characterization Approach for Behavior Modeling and Correction of Dynamic Nonlinear Transmitters , 2007, IEEE Transactions on Instrumentation and Measurement.

[6]  R Darraji,et al.  A Dual-Input Digitally Driven Doherty Amplifier Architecture for Performance Enhancement of Doherty Transmitters , 2011, IEEE Transactions on Microwave Theory and Techniques.

[7]  R. Neil Braithwaite,et al.  An improved Doherty amplifier using cascaded digital predistortion and digital gate voltage enhancement , 2009, 2009 IEEE MTT-S International Microwave Symposium Digest.

[8]  Jaewoo Sim,et al.  Analysis and Design of Doherty Power Amplifiers for Digital Pre-distortion Linearizer , 2007, 2007 Asia-Pacific Microwave Conference.

[9]  F.M. Ghannouchi,et al.  Design Optimization and DPD Linearization of GaN-Based Unsymmetrical Doherty Power Amplifiers for 3G Multicarrier Applications , 2009, IEEE Transactions on Microwave Theory and Techniques.

[10]  Chul Soon Park,et al.  Analysis and Implementation of Doherty Power Amplifier With Two-Point Envelope Modulation , 2012, IEEE Transactions on Microwave Theory and Techniques.

[11]  Gaoming Xu,et al.  High-Accuracy Bias Control Software for Doherty RF Power Amplifiers , 2011, 2011 7th International Conference on Wireless Communications, Networking and Mobile Computing.

[12]  C. Fager,et al.  Digital predistortion for dual-input Doherty amplifiers , 2012, 2012 IEEE Topical Conference on Power Amplifiers for Wireless and Radio Applications.

[13]  S. Carichner,et al.  An Improved Doherty Amplifier Using Cascaded Digital Predistortion and Digital Gate Voltage Enhancement , 2009, IEEE Transactions on Microwave Theory and Techniques.