Microstrip Line Modeling Taking into Account Dispersion Using a General-Purpose SPICE Simulator
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsDear Author,
This manuscript presents a valuable contribution to the field of microstrip line modeling, particularly due to its practical approach and utilization of widely accessible tools. While the methodology is well-developed and holds significant utility for engineering applications, some improvements could further strengthen the work—namely, more detailed implementation specifics and a clearer discussion of limitations. The subject covered in this article will interest the Journal of Low Power Electronics and Applications readers and may be suitable for publication after minor revisions. Below are my specific comments:
Comment 1: English correction is required.
Comment 2: Lines 16-17 – …,, The circuits with distributed parameters are the necessary part…” – References [1–3] do not contain a critical analysis of existing solutions. Please cite supporting literature of the study or studies that deal with this, but if there are none, then rephrase the beginning of the introduction in a different way.
Comment 3: Lines 19-20 – …,,devices are impossible to implement at these frequencies… – Please add quantitative data on lumped element limitations (Q-factor, tolerances).
Comment 4: Lines 16-91 – The introduction is concise but lacks a clear explanation of the scientific motivation. Specifically, it fails to quantify the practical impact of these limitations on modern systems. You should explicitly define the research gap by contrasting current solutions with unmet technical needs.
Comment 5: Line 127-128 – Equation (4) appears incomplete as it doesn't account for the effective permittivity (ε_eff) of the microstrip structure. The frequency dependence of β should be more explicitly addressed, particularly considering how ε_eff varies with frequency due to dispersion effects in microstrip lines.
Comment 6: Line 256 – Please complete the explanation for Figure 9 in the text below Figure 9 FR-4 parameters are well specified, but the GaAs substrate lacks loss tangent (tanδ).
Comment 7: Lines 280-300 – Conclusions – The conclusion contains all the necessary elements, but lacks technical precision. Please provide numerical values ​​that quantify the accuracy of the model. A brief comparison with other models regarding simulation speed, high-frequency accuracy, and implementation complexity should also be included. This will help readers understand when XSPICE is the optimal choice
Comment 8: Although the cited references are thematically relevant, only 12% are from the last five years (after 2019), with a significant lack of those on recent advances in SPICE-based dispersion modeling. The absence of self-citation is appropriate, but including reference studies from the period 2020–2024 would better position the model’s novelty against contemporary techniques.
Comments for author File: 
Comments.pdf
Please check your English, it's best to use Grammarly
Author Response
Comment 1: English correction is required. –
Response 1: Agree. Spelling and grammar revised in the entire text.
Comment 2: Lines 16-17 – …,, The circuits with distributed parameters are the necessary part…” – References [1–3] do not contain a critical analysis of existing solutions. Please cite supporting literature of the study or studies that deal with this, but if there are none, then rephrase the beginning of the introduction in a different way.
Response 2: Agree. Citation replaced (line 15)
Comment 3: Lines 19-20 – …,,devices are impossible to implement at these frequencies… – Please add quantitative data on lumped element limitations (Q-factor, tolerances).
Response 3: Agree. Added more detailed note on lumped devices limitations. Added a citation providing numeric data. (line 20-23)
Comment 4: Lines 16-91 – The introduction is concise but lacks a clear explanation of the scientific motivation. Specifically, it fails to quantify the practical impact of these limitations on modern systems. You should explicitly define the research gap by contrasting current solutions with unmet technical needs.
Response 4: Agree. Added notes on research novelty (lines 59-64 and 93-98)
Comment 5: Line 127-128 – Equation (4) appears incomplete as it doesn't account for the effective permittivity (ε_eff) of the microstrip structure. The frequency dependence of β should be more explicitly addressed, particularly considering how ε_eff varies with frequency due to dispersion effects in microstrip lines.
Response 5: Agree. Equation corrected. The full equations for ε_eff is beyond the scope of the paper. Added reference providing typical dependency [32,33].
Comment 6: Line 256 – Please complete the explanation for Figure 9 in the text below Figure 9 FR-4 parameters are well specified, but the GaAs substrate lacks loss tangent (tanδ).
Resposne 6: Agree. Added reference to GaAs substrate parameters.
Comment 7: Lines 280-300 – Conclusions – The conclusion contains all the necessary elements, but lacks technical precision. Please provide numerical values ​​that quantify the accuracy of the model. A brief comparison with other models regarding simulation speed, high-frequency accuracy, and implementation complexity should also be included. This will help readers understand when XSPICE is the optimal choice
Response 7: Agree. Added simulation speed benchmark (Table 1) and numeric simulation precision estimation (Table 5). These results results reflected in Conclusion.
Comment 8: Although the cited references are thematically relevant, only 12% are from the last five years (after 2019), with a significant lack of those on recent advances in SPICE-based dispersion modeling. The absence of self-citation is appropriate, but including reference studies from the period 2020–2024 would better position the model’s novelty against contemporary techniques.
Response 8: Agree. More citation of the papers published in recent five years added. Now 28 cited paper of 43 (65%) are published in the year range from 2020 to 2025. These citations are: [1-5,7,9-12,15-16,18-19,24-26,28,32,33,36,38,40-42]. Added a paragraph (lines 59-64) with a review of a novel circuit simulation methods of the structures with distributed parameters.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe paper presents the development of XSPICE models for microstrip lines, both single and coupled, that account for dispersion and impedance dependence on frequency. These models enable radio frequency (RF) simulations using open-source tools, such as Ngspice and Qucs-S. This is extremely valuable for academic research and OpenPDK-based projects. One significant advantage of this work is its practical nature. The author demonstrates how the models operate using a real LNA amplifier as an example and compares the results with data obtained from commercial tools (AWR and Scikit-RF), indicating solid functional validation. The models are publicly available, increasing their value to the community. However, the paper requires several corrections before publication. In my opinion, the corrections are as follows:
1) Many fragments contain typos and incorrect grammar (more details in a separate comment), so I recommend having the text proofread by a native speaker or a technical editor.
2) The description of the XSPICE models is sometimes difficult to follow, especially for readers unfamiliar with XSPICE. Therefore, the pseudocode should be shortened and tidied up, and a block diagram describing the data flow should be added.
3) The article barely addresses the potential limitations of XSPICE models (e.g., stability and computational efficiency).
4) Some of the graphs (e.g., figures 7–10) have low resolution or an inconsistent labeling style. Readability should be improved by standardizing the fonts, axes, descriptions, and legends.
5) There is no reference in the main text to Figure 3.
Comments on the Quality of English Language
The article contains numerous language errors that affect its readability and professional perception. Many are typical typos, such as “simulaiton” instead of “simulation,” “dimentions” instead of “dimensions,” or ‘eveluated’ instead of “evaluated.” There are also grammatical errors, such as incorrect use of prepositions (“the Figure 10” instead of “Figure 10”), or incorrect syntax (“XSPICE allows to define...” instead of “XSPICE allows defining...” or “...allows users to define...” ). The style of statements is sometimes imprecise or colloquial, such as “in case of educational tasks” instead of the more natural “for educational purposes.” Some wording is clumsy or unclear, e.g. “This leads to the rise of delay and distortion” - it would be better to write “This results in increased delay and signal distortion.” Linguistic problems do not prevent understanding of the content, but they significantly impede it. Full linguistic proofreading by a person proficient in technical English is recommended to improve the clarity, fluency and consistency of the text before publication.
Author Response
Comment 1: Many fragments contain typos and incorrect grammar (more details in a separate comment), so I recommend having the text proofread by a native speaker or a technical editor. – Response 1: Agree. Spelling and grammar revised in the entire text.
Comment 2: The description of the XSPICE models is sometimes difficult to follow, especially for readers unfamiliar with XSPICE. Therefore, the pseudocode should be shortened and tidied up, and a block diagram describing the data flow should be added.
Response 2: Agree. Added dataflow diagram Fig.5 with explanations.
Comment 3: The article barely addresses the potential limitations of XSPICE models (e.g., stability and computational efficiency).
Response 3: Added simulation speed benchmark (Table 1) and numeric simulation precision estimation (Table 5). Added note on XSPICE limitations in conclusion. The newly added numeric data referenced in conclusion.
Comment 4: Some of the graphs (e.g., figures 7–10) have low resolution or an inconsistent labeling style. Readability should be improved by standardizing the fonts, axes, descriptions, and legends.
Response 4: All figures in the article are the vector graphics (SVG). All figures uses the same font family. Low resolution raster graphics is not used. The size of figures adjusted. The PDF processed to embed fonts.
Comment 5: There is no reference in the main text to Figure 3.
Response 5: Agree. Reference added, the word “Figure” was missing. (line 151)
