Citation
Vasic, Miroslav and García Suárez, Oscar and Oliver Ramírez, Jesús Angel and Alou Cervera, Pedro and Díaz López, Daniel and Cobos Márquez, José Antonio
(2009).
Multilevel Power Supply for High Efficiency RF Amplifiers.
In: "24th Annual IEEE Applied Power Electronics Conference and Exposition, APEC 2009", 15/02/2009 - 19/02/2009, Washington, Estados Unidos . ISBN 978-1-4244-2811-3 .
https://doi.org/10.1109/APEC.2009.4802821.
Abstract
In radio systems linear power amplifiers (class A, B or AB) are usually used as a solution for the power amplifier stage. These amplifiers have high linearity, but suffer from low efficiency when the transmitted signal has low peak-to-average power ratio. The Kahn envelope elimination and restoration (EER) technique is used to enhance efficiency of RF transmitters, by combining highly efficient, nonlinear RF amplifier (class D or E) with a highly efficient envelope amplifier in order to obtain linear and highly efficient RF amplifier. This paper presents a solution for the envelope amplifier based on a combination of multilevel converter and linear regulator. The proposed solution can reproduce any signal with maximal spectral component of 2 MHz and give instantaneous maximal power of 50 W. The efficiency measurements show that when the signals with low average value are transmitted, it has up to 15% higher efficiency than linear regulator that is used as a conventional solution. Additionally, the algorithm for selection of voltage levels for the multilevel converter is explained, as well.
