A fully integrated parallel stages converter for thermal energy harvesting

In this paper a fully integrated DC/DC converter for Thermal Energy Harvesting is presented, it is based on a parallel stages architecture as a technique to increase the conversion efficiency without using frequency or duty cycle modulation. The circuit was designed for a CMOS 180 nm process, with an active area of 954μm×341μm\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$954\,\upmu {\mathrm{m}} \times 341\,\upmu {\mathrm{m}}$$\end{document}. The post-layout simulation shows a 87%\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\%$$\end{document} peak efficiency with 1.2 V for a minimum operating input voltage of 250 mV at 33 kHz of switching frequency.