AM/AM and AM/PM Characterization of a GaN Phase and Amplitude Setting Circuit

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

 

This manuscript presents the measurement method and results of AM/AM and AM/PM of phase and amplitude setting circuit for high power application. This reviewer has the following comments.

 1. In Section I, the authors mentioned that there is no research on measurement methods for AM/AM and AM/PM in passive circuits. "No reported works are focused explicitly on AM/PM characterization for PAS circuits." Please, describe why there has been no research until now.

2. For high-power applications, the PAS circuit can be located in front of the high-power device to minimize the nonlinearity of the PAS circuit. Fig.6-8 shown in this manuscript confirms that the nonlinearity of PAS is minimized in the low-power region. Nevertheless, is there a systematic reason to check the PAS circuit for high power characteristics? There appears to be a lack of reason for placing PAS behind high-power devices. Additionally, since PAS utilized the GaN process, there appears to be a lack of feasibility in verifying the high-power characteristics of PAS.

 3. In Section I, many of the previously published nonlinearity measurement methods are PA. The papers on PA nonlinearity presented in the manuscript are not significantly related to the main idea of this study, so it seems possible to describe them briefly. It would be a good idea to add papers related to the nonlinearity of passive circuits and explain why the research is necessary.

 4. The measured AM/AM and AM/PM results include the nonlinearity of the drive amplifier. In order to check the nonlinearity of the PAS, can't it be possible to check the nonlinearity of the PAS only by compensating for the nonlinearity of the drive amplifier?

 5. Fig.6 shows the nonlinearity of the PAS and drive amplifier. Is it possible to accurately describe whether this is a non-linearity that occurs because PAS is a high-power application or a non-linearity that occurs because the non-linearity of the drive amplifier increases?

6. In section IV, the nonlinearity of PAS was measured using the presented measurement method. Could the nonlinearity of the PAS be predicted through simulation to ensure that it was measured sufficiently accurately? So, is it possible to compare the nonlinearity of PAS between simulation and measurement data?

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript presents a valuable contribution by delving into the non-linear characterization of a 6-bit Phase and 10 Amplitude Setting MMIC. The experimental setup employing three vector receivers enables comprehensive vector measurements with straightforward scalar correction. The study includes a detailed analysis of the 64-state constellation under varying input power levels, revealing observable static AM/AM and AM/PM distortion effects, such as 3 dB gain compression and 2.7 degrees of phase conversion at 36 dBm input power. This research significantly advances our understanding of MMIC behavior in non-linear regimes and offers insights into potential mitigation strategies. The manuscript is well written, but some minor mistakes can be addressed, which can improve their work. Therefore, I recommend that the authors revise their manuscript according to the comments below.

#1 The abstract is too short. However, a good abstract should not exceed 150 words. Adds quantitative relevant informations to the abstract. I recommend authors use the following reference to adjust their abstract (https://doi.org/10.1016/j.carbon.2007.07.009).

#2 There are some grammatical mistakes which should be corrected. Please check the manuscript grammar and cohesion as a whole.

#3 The novelty of the work is not expressed explicate in a full way. In which aspect this work is original and better than others?

#4 The introduction proposed by the authors has to be improved. Please restructure the manuscript introduction dividing it into five parts as follows: (a) Research motivation, (b) literature review, (c) the necessity of the research based on challenges of the literature, and (d) novelty and main contributions of the paper.

#5 A comprehensive comparative analysis is essential for this study. To effectively validate the new method proposed in this work, it is strongly recommended to provide a detailed comparative table. This table should include relevant parameters, results, and findings obtained from the new method, alongside those from previously established methods in the field. By presenting this comparative table, readers will have a clear and concise overview of how the new method performs in comparison to existing approaches. This comparative analysis will greatly contribute to the validation and evaluation of the proposed method, reinforcing its novelty and potential advantages.

#6 Please replace old references by latest ones. As can be seen, only 7 of 37 references are listed as new references (2019-2023), which is unsuitable. At least 75% of the references of a modern manuscript should be between 2019-2023. Check your references.

Comments on the Quality of English Language

Some minor mistakes need attention. 

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

In this work, the authors proposed a test bench consisting of three vector receivers and an absolute power reference to characterize the static amplitude-to-amplitude (AM/AM) conversion and amplitude-to-phase (AM/PM) conversion of a 6-bit Phase and Amplitude Setting circuits (PAS) MMICs. The deviation from the linear behavior of the device under test (DUT) was analyzed by using the test bench. This work is of interest to other researchers in scientific and engineering community of microwave and millimeter wave circuits. I would like to give some comments and suggestions. Hopefully authors might find them useful towards revision. The detailed comments are as follows:

1) In introduction, the authors write: “Gallium Nitride (GaN) has become the industry standard semiconductor for microwave and millimeter wave circuits in high-end electronic systems utilised in space communications. More specifically, GaN technology is nowadays used for signal conditioning, shaping and generation circuits, including mixers[1], [2], voltage-controlled oscillators (VCO) [3], [4], phase shifters (PS) [5]–[8] and attenuators (ATT) [9] at microwave and millimeter wave frequencies.” The introduction has much room to be improved. Besides microwave and millimeter wave circuits in high-end electronic systems, GaN has been widely used to build optoelectronic devices including laser and LEDs. It would be great if the authors include these developments and achievements in the introduction, so to give the readers a much broader view. Several recent references concerning on the MOCVD epitaxy of GaN in applications of laser and LEDs, such as Science 319(5862), 445-447 (2018) (https://doi.org/10.1126/science.1150413); Laser & Photonics Reviews 2023, 2300464 (https://doi.org/10.1002/lpor.202300464); Laser & Photonics Reviews 2023, 17, 2200455 (https://doi.org/10.1002/lpor.202200455), etc. should be added, so that the readers can be clear about the state-of-the-art of this topic.

2) Please check the location of abbreviation in the main text, like MMICs. The authors should define the full name when the abbreviation first occurs in the text.

3) Figure 3 and figure 4 are unclear, which is difficult for readers to understand structure of the test bench.

4) What are the differences between AM/AM static characteristics and AM/PM static characteristics of device under test? From my perspective, the authors should analyze the differences in detail.

5) I recommend the authors label the detailed structure of relay board interface in figure 5. Therefore, the readers can more easily understand the structure of relay board interface.

6) What are the meanings of asterisks and circles with different colors in figure 8?

Author Response

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Author Response File: Author Response.pdf