Hybrid Modulated DCDC Boost Converter for Wearable Devices

Round 1

Reviewer 1 Report

This paper proposed a DCDC boost converter with a hybrid DGM/PCMC-PFM/PCMC-PWM modulation technique，which can achieve high conversion efficiency over a wide load range.  The result of the study is very useful for wearable devices. There are a lot of abbreviations in the manuscript, it is suggested that the abbreviation be annotated.

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Authors propose a DCDC boost converter which uses a hybrid modulation of DGM, PCMC-PFM and PCMC-PWM. The converter switches smoothly from PCMC-PFM to PCMC-PWM mode under load current based conditions and without any mode selection module. The proposed DCDC boost converter has been fabricated in a 0.18um CMOS process, the input voltage ranges within 0.8-5V, for an output voltage equals to 5V, while the load current range is 5-300mA. Experimental results show that the boost converter can achieve 94.7% peak efficiency.

The proposed converter is interesting, the paper is well-organized while english proof-reading is strongly suggested. Various typos are present along the paper, to give some example: the last sentence of the abstract is closed with two dots; "shown" is repeated in line 204; "load" seems wrongly written in Fig. 1 and so on.

Introduction gathers a good number of references, but there is enough room to input further works. Reviewer would suggest some papers which deal with this topic. Being the proposed solution a monolithic boost converter targetted to wereable applications other kind of topologies, different from the switched inductor ones, should be reported. For example, switched capacitor-based converters, like charge pumps, can be adopted in this field. Even if the power conversion efficiency is typically lesser than the switched inductor counter-part, the absence of the magnetic component makes these solution suitable for fully-monolithic implementations. Some papers are listed as example in the following:

- A review of charge pump topologies for the power management of IoT nodes (review)

- A subthreshold cross-coupled hybrid charge pump for 50-mV cold-start 

- Current-mode body-biased switch to increase performance of linear charge pumps 

(both particularly suited for wearable applications whose energy autonomy is based on TEG)

Further comments are here reported:

1) I respectfully ask to me if the wearable applications are a good application field for the proposed converter. It is right that the proposal is an IC but there are two external components (the input inductor and the output capacitor) which can determine difficulties in wearability of the circuit. Can I suggest to add further possibilities of application for the proposed system ?

2) By inspection of Fig. 2, the error amplifier has the signal Vref2 applied to its non inverting input, but eq. (1), which describes the output voltage of the error amplifier, has Vref1 in the second term. Is it a typo?

3) Output voltage (i.e. Vco - Resr*Iload) in eq. 1 appears only when the output capacitor feeds the load, but what if the converter charges the capacitor and, simultaneously, feeds the load ? Can the authors spend some words about this case ?

4) Sub-circuit and electrical quantities related to the pulse generator have the subscript "PLUSE", is it a typo or not ?

5) Being the proposed circuit a DC-DC converter, information about line and load regulations should be reported. Please, provide them.

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

I have carefully read the article called "Hybrid Modulated DCDC Boost Converter for Wearable Device".

The article is ripe to be presented to the scientific community, I have only some doubts about its form.

My recommendations are that the authors check all acronyms used and not defined before. The article tends to look like a datasheet rather than a scientific discussion article. The units of measurement are simplified, the micro symbol does not appear, and then there is no space after the number and the unit of measurement. Similarly, the authors have to change some figures which, like figure 6, seem to have been taken from a datasheet.

A more suitable scientific form is advisable, although the scientific content is full and mature.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Dear Authors, thank you for your profitably response. In my opinion, the paper can be accepted for publishing in this journal.