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Applying Vacuum Tube Devices
Published in Jerry C. Whitaker, Power Vacuum Tubes, 2017
The key aspect of the Doherty circuit is the change in load impedance on tube V1 with modulation. This property enables the device to deliver increased output power at a constant plate voltage swing. The result is high efficiency and good linearity. Overall efficiency of the Doherty amplifier ranges from 60% to 65%.
Asymmetrical Doherty power amplifier using ferroelectric ceramics for linearity enhancement
Published in Electromagnetics, 2018
Shiwei Zhao, Xiaoqi Zhou, Yi Ren, Yuehang Xu
Several techniques have been presented in Doherty amplifier investigation to overcome such a tradeoff. The technique based on peak-power controlling technique for enhancing digital per-distortion of RF power amplifier (Nader et al. 2012), and compensation of peak amplifier phase variation using accurate offset line design (Kim et al. 2016), the enhanced back-off efficiency mode is also proposed to improve efficiency and linearity (Cho et al. 2014). Besides, post-distortion linearization technique is used to improve linearity (Tsai and Huang 2007), but, these methods are increased level of design complexity. In addition, some asymmetrical methods is proposed for enhancing linearity, such as optimum operation of asymmetrical-cells-based and optimized asymmetrical DPA (Kim et al. 2005, 2011), Besides, the inverted asymmetric DPA driven by two-stage symmetric Doherty amplifier is also proposed (Chun et al. 2010), the higher-order inter-modulation distortion products can be self-compensated, so the linearity of DPA is improved, however, above some methods, the phase of DPA cannot be change flexibly according to desired, so the application in engineering is limited.
A high-efficiency Doherty Power Amplifier for wireless base stations
Published in International Journal of Electronics Letters, 2021
The ideal Doherty amplifier design uses the load impedances of the carrier amplifier (Zc) and peaking amplifier (Zp) expressed as (Sun et al., 2013) in Eq. (1) and Eq. (2):