A.O. Pergushev1, V.A. Sorotsky2

1,2 Peter the Great St. Petersburg Polytechnic University (St. Petersburg, Russia)

1 pergushev.aleksey@mail.ru; 2 sorotsky@mail.spbstu.ru

The method of amplifying signals with a high peak-to-average power ratio, based on the combined use of automatic supply voltage regulation and outphasing methods, allows to significantly expand the bandwidth of the switching-mode power amplifier (PA). This possibility appears because the envelope tracking power supply (ETPS) solves the problem of obtaining the required dynamic range of the signal, as it is accepted in the Kahn method. However, unlike the latter, this is achieved with a significantly narrower bandwidth and, accordingly, a lower frequency of the PWM reference voltage, which causes efficiency improvement. At the same time, the solution to the main problem (expansion of the PA bandwidth) should be provided by the dephasing channel. In addition, its efficiency can also be improved, since the dynamic range of the signal amplified in this channel becomes much smaller.

The objective of the paper is to research the spectral and power characteristics of the PA, implemented on the basis of this principle. The research outcomes include the parameters of the amplifier optimal operating mode, at which maximum efficiency is achieved and the level of nonlinear distortion is reduced.

It has been found that the level of out-of-band distortions in the output signal of the combined PA is no more than 10 dB higher than in the signal of the amplifier using the Kahn method. At the same time, it is 10…15 dB lower than in the amplifier based on the outphasing method.

It has been shown that when the bandwidth of the combined amplifier is expanded by 4...5 times, the level of parasitic out-of-band spectral components can increase by 10...20 dB. In this case, the maximum efficiency and minimum spectral distortions are achieved with the bandwidth of the low-frequency envelope shaper in the combined amplifier equal to a quarter of the amplified signal frequency band. To reduce out-of-band distortions, it is recommended to use signal predistortion.

Pergushev A.O., Sorotsky V.A. Spectral distortions and power efficiency of a switching-mode power amplifier with an extended bandwidth when amplifying signals with a high peak‑to‑average power ratio. Radiotekhnika. 2025. V. 89. № 3. P. 90−97. DOI: https://doi.org/10.18127/j00338486-202503-08 (In Russian)

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