A low power low noise analog front-end for ECG recording

This work presents a power-efficient and noise-efficient amplifier for ECG recordings. To improve power efficiency, all the transistors in the proposed amplifier is designed in sub-threshold region which gives high gm\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_m$$\end{document}/ID\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_D$$\end{document} ratio. To improve noise efficiency, inverter-based differential input stage is used in this proposed operational transconductance amplifier as it reduces noise by a factor of 2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sqrt{2}$$\end{document} when compared to it’s non-inverter based counterpart. In order to decrease flicker noise, large transistors are used in the input stage. Class A–B structure is used in the output stage for achieving high gm\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_m$$\end{document}/ID\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_D$$\end{document} ratio and for large output swing range. In 180 nm process the amplifier consumes 477 nW DC power from 1.8 V supply which indicates 7.5% decrease in power consumption when compared to recently reported papers. This amplifier achieves a noise efficiency of 2.68. Common mode rejection ratio and power supply rejection ratio is estimated as 98.5 dB and 104.5 dB respectively.