High-Efficiency GaN-Based Power Amplifiers for Envelope Nonlinearities’ Mitigation in VHF Wideband Polar-Mode Transmitters

Round 1

Reviewer 1 Report

The authors could state more on what is meant by wide fractional bandwidth. Although multi-carrier communications at VHF have been around for a long time, it's usage in satellite communications is probably more recent. Could the authors please clarify, the difference in its use in satellite communications.

Some very minor grammatical mistakes.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Specific comments and recommendations:

1) The authors of this manuscript have to describe in more detail how an amplitude-modulated signal is obtained since amplifiers operating in class D use a switchable power stage - the output transistors operate in pulse mode;

2) How to mathematically obtain a modulated signal at the output using a resonant circuit. Are there higher harmonics in the signal spectrum? What is the effect of changing the load on the work process?

3) How can linearity be increased and non-linear distortions reduced accordingly - how is linearity defined?

4) How would the operation of the proposed circuit change when the load is bridged?

Minor editing of English language required.

Author Response

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Reviewer 3 Report

The authors present a very ample work on GaN-based power amplifiers. The manuscript is well written and very exhaustive.

I have some minor comments that the authors could consider:

 

1) The data in Figure 7 should be better organized. The y-axis lower limit is too low and 3/10 of the plot is empty. Font size is too small. The figure should be better discussed.

 

 2) Data in Figure 11b: "distribution of envelope frequency components compared with the gain of the linear EA," data in Figure 12: "Spectra of the envelope of a 4C-CH VDL-T" and data in Figure 13: "SEPS slow envelope DPWM."

Would it be possible to perform a fit of the trend? It looks like that there is a cut-off behaviour.

 

3) Is it possible to add in the conclusion a daily life application of the studied amplifiers?

Author Response

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