Outphasing Energy Recovery Amplifier With Resistance Compression for Improved Efficiency

• Published in: IEEE transactions on microwave theory and techniques Vol. 57; no. 12; pp. 2895 - 2906
• Main Authors: Godoy, P.A., Perreault, D.J., Dawson, J.L.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.12.2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Amplifiers; Applied sciences; Circuit properties; Compressing; Efficiency; Electric, optical and optoelectronic circuits; Electronic circuits; Electronic equipment and fabrication. Passive components, printed wiring boards, connectics; Electronics; Energy recovery; Exact sciences and technology; Frequency; High power amplifiers; Impedance; Linear amplification with nonlinear components (LINC); Linearity; Microwaves; outphasing; Ports; Power amplifiers; Power generation; Power supplies; Prototypes; radio-frequency (RF) power amplifier; Rectifiers; resistance compression; Resistors; Performance evaluation; radio-frequency (RF) power amplifier; Quadrature amplitude modulation; Prototype; Output power; Linear amplification; Peak to average power ratio; Power supply; Implementation; outphasing; Radiofrequency amplifiers; Peak power; Resistor; Rectifier; Linear amplification with nonlinear components LINC; System design; Energy recovery; Power electronics; Radiofrequency; Switching; Combiner circuit; resistance compression; Operating rate; Linearity; Power amplifier; Impedance
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2009.2033976

We describe a new outphasing energy recovery amplifier (OPERA) which replaces the isolation resistor in the conventional matched combiner with a resistance-compressed rectifier for improved efficiency. The rectifier recovers the power normally wasted in the isolation resistor back to the power supply, while a resistance compression network (RCN) reduces the impedance variation of the rectifier as the output power varies. Because the combiner requires a fixed resistance at the isolation port to ensure matching and isolation between the two outphased power amplifiers (PAs), the RCN serves to maintain high linearity as well as high efficiency in the switching-mode PAs. For demonstration, a prototype OPERA system is designed and implemented with discrete components at an operating frequency of 48 MHz, delivering 20.8 W peak power with 82.9% PAE. The measurement results show an efficiency improvement from 17.9% to 42.0% for a 50-kHz 16-QAM signal with a peak-to-average power ratio of 6.5 dB.