\documentclass[border=0mm]{standalone}

\usepackage{cmap}
\usepackage[cp1250]{inputenc}	
\usepackage[T1]{fontenc}
\usepackage{graphicx}
\usepackage{lmodern}
\usepackage{tikz}
\usepackage{float}
\usepackage{siunitx}
\usepackage{amsmath}
\usepackage{upgreek}
\usepackage{pgfplots}
\pgfplotsset{compat=1.17}
\usepgfplotslibrary{fillbetween}
\usepgfplotslibrary{units}
% \makeatletter
%\pgfplotsset{
%  unit code/.code 2 args=
%    \begingroup
%    \protected@edef\x{\endgroup\si{#2}}\x
%} 
%\makeatother

\pgfkeys{%
  /tikz/on layer/.code={
    \pgfonlayer{#1}\begingroup
    \aftergroup\endpgfonlayer
    \aftergroup\endgroup
  }
}

\begin{document}
	\begin{tikzpicture}
		\begin{axis}[
			height=7cm,	width=11cm,	grid=major,
    		x unit=\SI{}{\degreeCelsius}, y unit=\SI{}{\volt},
			xlabel=Temperature,	ylabel={$V_\mathrm{CPO}$},
			%ymin=0.52,ymax=0.7,
			xmin=-45, xmax=130,			
			%ytick distance = 0.02,
			xtick = {-45,-25,0,25,50,75,100,130},
			set layers,
			%y tick label style={/pgf/number format/.cd, set thousands separator={}},
			xticklabel shift = 2 pt,
			legend pos=north west,
			 /pgf/number format/.cd,
            fixed,
            precision=3,
        /tikz/.cd
		]			

\addplot +[solid,smooth,thick,color=blue,mark=none] table [x expr=\thisrow{temp}, y expr=\thisrow{dll_1v2}*1e-6, col sep=comma] {../cadence_data/dll_freq_nomR.csv};
			%\addlegendentry{constant current bias};
			
			\addplot +[solid,smooth,thick,color=red,mark=none] table [x expr=\thisrow{temp}, y expr=\thisrow{1v2}*1e-6, col sep=comma] {../cadence_data/dll_freq_hindif.csv};
			%\addlegendentry{constant current bias};	
			
			\addplot +[solid,smooth,thick,color=black,mark=none] table [x expr=\thisrow{temp}, y expr=\thisrow{1v2}*1e-6, col sep=comma] {../cadence_data/dll_freq_londif.csv};
			%\addlegendentry{constant current bias};
			
			\addplot +[name path = cvo_1v08,smooth,solid,thick,color=blue,mark=none, draw=none] table [x expr=\thisrow{temp}, y expr=\thisrow{dll_1v08}*1e-6, col sep=comma] {../cadence_data/dll_freq_nomR.csv};
			\addplot +[name path = cvo_1v32,smooth, solid,thick,color=blue,mark=none, draw=none] table [x expr=\thisrow{temp}, y expr=\thisrow{dll_1v32}*1e-6, col sep=comma] {../cadence_data/dll_freq_nomR.csv};
			
			\addplot +[name path = cvo_1v08_hindif,smooth,solid,thick,color=blue,mark=none, draw=none] table [x expr=\thisrow{temp}, y expr=\thisrow{1v08}*1e-6, col sep=comma] {../cadence_data/dll_freq_hindif.csv};
			\addplot +[name path = cvo_1v32_hindif,smooth, solid,thick,color=blue,mark=none, draw=none] table [x expr=\thisrow{temp}, y expr=\thisrow{1v32}*1e-6, col sep=comma] {../cadence_data/dll_freq_hindif.csv};
			
			\addplot +[name path = cvo_1v08_londif,smooth,solid,thick,color=blue,mark=none, draw=none] table [x expr=\thisrow{temp}, y expr=\thisrow{1v08}*1e-6, col sep=comma] {../cadence_data/dll_freq_londif.csv};
			\addplot +[name path = cvo_1v32_londif,smooth, solid,thick,color=blue,mark=none, draw=none] table [x expr=\thisrow{temp}, y expr=\thisrow{1v32}*1e-6, col sep=comma] {../cadence_data/dll_freq_londif.csv};
			
			%\addplot[blue, fill opacity = 0.2] fill between[of=cvo_1v08 and cvo_1v32];
			%\node [blue!50!black] at (axis cs:80,0.62) {nominal};
			%\addplot[red, fill opacity = 0.2] fill between[of=cvo_1v08_hindif and cvo_1v32_hindif];
			%\node [red!50!black] at (axis cs:80,0.69) {high Ndif, low Ppoly};
			%\addplot[black, fill opacity = 0.2] fill between[of=cvo_1v08_londif and cvo_1v32_londif];
			%\node [black] at (axis cs:80,0.548) {low Ndif, high Ppoly};
			
			%\draw [<->,color=blue!60!black] (axis cs:0,0.595) -- node[above, pos = 0.9, color=blue!60!black]{$\pm 10\%\: V_\mathrm{DD}$ variation} (axis cs:0,0.609) ;
			
		\end{axis}
	\end{tikzpicture}
\end{document}