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High-Efficiency Power Amplifiers
Published in Choi Jung Han, Iniewski Krzysztof, High-Speed and Lower Power Technologies, 2018
Guillermo Velasco-Quesada, Herminio Martínez‑García, Alfonso Conesa-Roca
The second strategy also utilizes a DC/DC converter as a tracking power supply system which monitors the amplifier output voltage and adjusts the supply voltage accordingly. When the amplifier output voltage increases above a threshold value, the power supply system tracks the peak level of the output voltage and impose a supply voltage only slightly higher (ΔV) than the instantaneous value of the output voltage, as is shown in Figure 12.17b. When the amplifier output falls below the threshold value, the power supply system returns to its nominal output voltage value. As a consequence, power dissipation is greatly reduced compared to conventional class-AB amplifiers. This second strategy is used by the company Texas Instruments in their integrated amplifiers for piezoelectric actuators and ceramic speakers. These amplifiers are also referred to by some authors as amplifiers with tracking power supply, and their main operating principle is used in envelope-tracking amplifiers devoted to RF applications.
A Comprehensive Review on Supply Modulators and Control Strategies for Envelope Tracking RF Power Amplifiers in Mobile Communication
Published in IETE Journal of Research, 2023
Ambily Babu, B.G. Shivaleelavathi, Veeramma Yatnalli
A comprehensive literature survey of the supply modulators and control strategy for ETPA in mobile communication is presented in the paper. Various efficiency enhancement techniques in back-off region of operation are examined. Among other techniques, envelope tracking has emerged as an encouraging technology to enhance the efficiency of RF power amplifiers, operating in back-off region. Features of supply modulator topologies of ETPA like Linear, Switching and Hybrid are presented in detail. Currently, designers are focusing on obtaining power supply modulators that provide both high efficiency and bandwidth. Hybrid supply modulators provide good linearity, high efficiency, reduced noise ripples and high bandwidth and hence, are found to be the best choice of supply modulators for future ETPA in mobile communication. Features of the two main control strategies, PWM and Hysteretic control employed in hybrid supply modulators are discussed in the paper. State-of-the-art designs in hybrid supply modulators are also presented.