**5. Conclusions**

This paper proposed an AC-DC converter which does not require external components for rectification and power conversion. It can be integrated in the same IoT chip with a small overhead area of 0.1 mm<sup>2</sup> . This converter can provide a better option for electrostatic energy harvesting where the cost is the highest priority.

**Author Contributions:** Conceptualization, T.T.; methodology, Y.I. and T.T.; software, Y.I.; validation, Y.I. and T.T.; formal analysis, Y.I. and T.T.; investigation, Y.I. and T.T.; writing—original draft preparation, Y.I.; writing—review and editing, T.T.; funding acquisition, T.T. Both authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** This work is supported by d-lab.VDEC, Synopsys, Inc., Cadence Design Systems, Inc. Rohm Corp. and Micron Foundation. The authors wish to thank Associate M. Futagawa, H. Hirano and S. Ota for technical discussion.

**Conflicts of Interest:** The authors declare no conflict of interest.
