A digital Doherty transmitter suitable for wireless infrastructure efficiency enhancement

The present work proposes a digital Doherty power amplifier (PA) with improved efficiency performance. The efficiency enhancement is achieved by using a digital adaptive phase alignment mechanism that is implemented to address the problem of power-dependent phase imbalance between the carrier and peaking cells of gallium-nitride (GaN) Doherty PAs following the turn-on of the peaking cell. An average efficiency of 57% has been measured using a one-carrier Worldwide Interoperability for Microwave Access (WiMAX) signal with a peak-to-average power ratio of 7 dB. This corresponds to an improvement of 7% in average efficiency with no linearity degradation compared to a conventional single-input fully analog Doherty PA.

[1]  Ryo Ishikawa,et al.  A GaN HEMT Doherty amplifier with a series connected load , 2009, 2009 Asia Pacific Microwave Conference.

[2]  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.

[3]  Bumman Kim,et al.  A highly efficient Doherty power amplifier employing optimized carrier cell , 2009, 2009 European Microwave Conference (EuMC).

[4]  Franco Giannini,et al.  Efficiency improvement in Doherty power amplifier by using Class F approach , 2009, 2009 European Microwave Integrated Circuits Conference (EuMIC).

[5]  A. Z. Markos,et al.  Design of GaN HEMT based Doherty amplifiers , 2010, 2010 IEEE 11th Annual Wireless and Microwave Technology Conference (WAMICON).

[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]  Fadhel M. Ghannouchi,et al.  Comparative study of recent advances in power amplification devices and circuits for wireless communication infrastructure , 2009, 2009 16th IEEE International Conference on Electronics, Circuits and Systems - (ICECS 2009).

[8]  Hiroaki Deguchi,et al.  A 33W GaN HEMT Doherty amplifier with 55% drain efficiency for 2.6GHz base stations , 2009, 2009 IEEE MTT-S International Microwave Symposium Digest.

[9]  Mun-Woo Lee,et al.  A New Wideband Distributed Doherty Amplifier for WCDMA Repeater Applications , 2009, IEEE Microwave and Wireless Components Letters.