Two images side by side not centered

I have a Bode diagram composed of two graphs, I used two tikz environment instead of one, and I used minipage to put the graphs side by side. It works but the only problem is that it is not centered with the text. How can I fix that ? Do I have to work with only one tikz environment ?

documentclass[12pt,a4paper]{article}
usepackage[utf8]{inputenc}
usepackage[T1]{fontenc}
usepackage[margin=1in]{geometry}
usepackage{xcolor}
usepackage{graphicx,setspace}
renewcommand{baselinestretch}{1.5}
usepackage{tikz}
usetikzlibrary{angles, arrows.meta,
                quotes}
usetikzlibrary{fit,calc,positioning,decorations.pathreplacing,matrix}                
usepackage{pgfplots}
pgfplotsset{compat=1.16}


begin{document}
subsubsection{underline{textbf{$K_p > 1$} :}} on parle d'amplification, il y a un ajout de gain qui améliore la précision. D'autre part, une translation vers le haut du diagramme de la magnitude cause un élargissment de la bande passante et donc une amélioration de la rapidité.  
begin{figure}[h]
begin{minipage}[b]{0.5textwidth}
centering
begin{tikzpicture}
hspace{2mm}
begin{axis}[xmode=log,xmin=1e-1,xmax=1e4,ymin=-20,ymax=20,grid=both]
%normale
draw [blue] (axis cs:1e-1,8) ..controls (axis cs:10,8) .. (axis cs:1e4,-17);
node at (axis cs:0.2,9) {small color{blue} texttt{K=1}};
%K>1
draw [green] (axis cs:1e-1,12) .. controls (axis cs:10,12) .. (axis cs: 1e4,-13);
node at (axis cs:0.2,13) {small color{green} texttt{K>1}};
%K<1
draw [red] (axis cs: 1e-1,4) .. controls (axis cs:10,4) .. (axis cs: 8000, -20);
node at (axis cs:0.2,5) {small color{red} texttt{K<1}};
%0dB
draw [thick] (axis cs:1e-1,0) -- (axis cs:1e4,0);
%omega c red
draw [red, dashed] (axis cs:20,0) -- (axis cs:20,-20);
node at (axis cs:13,-1) {scriptsize color{red} texttt{$omega_c$}};
%omega blue
draw [blue, dashed] (axis cs:80,0) -- (axis cs:80,-20);
node at (axis cs:65,-1) {scriptsize color{blue} texttt{$omega_c$}};
%omega green
draw [green, dashed] (axis cs:260,0) -- (axis cs:260,-20);
node at (axis cs:240,-1) {scriptsize color{green} texttt{$omega_c$}};
end{axis}
%fill (5.38,5.4) node[draw] {color{gray} texttt{Magnitude(dB)}};
end{tikzpicture}
end{minipage}
begin{minipage}[b]{.5textwidth}
centering
begin{tikzpicture}
begin{axis}[xmode=log,xmin=1e-1,xmax=1e4,ymin=-180,ymax=-60,grid=both]
%phase
draw [blue] (axis cs:1e-1,-70) .. controls (axis cs:50,-70) and (axis cs: 50,-180)..(axis cs:1e4,-180);
%marge Phi blue
draw [>=stealth,blue,->] (axis cs:80,-180) -- (axis cs:80,-137);
node at (axis cs:55,-158) {small color{blue} texttt{$M_Phi$}};
%marge Phi Red
draw [>=stealth,red,->] (axis cs:20,-180) -- (axis cs:20,-110);
node at (axis cs:12,-150) {small color{red} texttt{$M_Phi$}};
%marge Phi green
draw [>=stealth,green,->] (axis cs:260,-180) -- (axis cs:260,-157);
node at (axis cs:150,-170) {small color{green} texttt{$M_Phi$}};
end{axis}
%phase
fill (5.9,5.4) node[draw] {color{gray} texttt{Phase($^circ$)}};
%figure
%node at (3.5,-0.8) {small  texttt{fréquence angulaire (rad/s)}};
%node at (3.5,-1.25) {small color{blue} texttt{fig 12}};
end{tikzpicture}
end{minipage}
caption{Diagramme de Bode du correcteur proportionnel}
end{figure}
end{document}

documentclass[12pt,a4paper]{article}
usepackage[utf8]{inputenc}
usepackage[T1]{fontenc}
usepackage[margin=1in]{geometry}
usepackage{xcolor}
usepackage{graphicx,setspace}
renewcommand{baselinestretch}{1.5}
usepackage{tikz}
usetikzlibrary{angles, arrows.meta,
                quotes}
usetikzlibrary{fit,calc,positioning,decorations.pathreplacing,matrix}                
usepackage{pgfplots}
pgfplotsset{compat=1.16}


begin{document}
subsubsection{underline{textbf{$K_p > 1$} :}} on parle d'amplification, il y a un ajout de gain qui améliore la précision. D'autre part, une translation vers le haut du diagramme de la magnitude cause un élargissment de la bande passante et donc une amélioration de la rapidité.  
begin{figure}[h]
begin{minipage}[b]{.5textwidth}
centering
begin{tikzpicture}[scale=.8]
hspace{2mm}
begin{axis}[xmode=log,xmin=1e-1,xmax=1e4,ymin=-20,ymax=20,grid=both]
%normale
draw [blue] (axis cs:1e-1,8) ..controls (axis cs:10,8) .. (axis cs:1e4,-17);
node at (axis cs:0.2,9) {small color{blue} texttt{K=1}};
%K>1
draw [green] (axis cs:1e-1,12) .. controls (axis cs:10,12) .. (axis cs: 1e4,-13);
node at (axis cs:0.2,13) {small color{green} texttt{K>1}};
%K<1
draw [red] (axis cs: 1e-1,4) .. controls (axis cs:10,4) .. (axis cs: 8000, -20);
node at (axis cs:0.2,5) {small color{red} texttt{K<1}};
%0dB
draw [thick] (axis cs:1e-1,0) -- (axis cs:1e4,0);
%omega c red
draw [red, dashed] (axis cs:20,0) -- (axis cs:20,-20);
node at (axis cs:13,-1) {scriptsize color{red} texttt{$omega_c$}};
%omega blue
draw [blue, dashed] (axis cs:80,0) -- (axis cs:80,-20);
node at (axis cs:65,-1) {scriptsize color{blue} texttt{$omega_c$}};
%omega green
draw [green, dashed] (axis cs:260,0) -- (axis cs:260,-20);
node at (axis cs:240,-1) {scriptsize color{green} texttt{$omega_c$}};
end{axis}
%fill (5.38,5.4) node[draw] {color{gray} texttt{Magnitude(dB)}};
end{tikzpicture}
end{minipage}
begin{minipage}[b]{.4textwidth}
centering
begin{tikzpicture}[scale=.8]
begin{axis}[xmode=log,xmin=1e-1,xmax=1e4,ymin=-180,ymax=-60,grid=both]
%phase
draw [blue] (axis cs:1e-1,-70) .. controls (axis cs:50,-70) and (axis cs: 50,-180)..(axis cs:1e4,-180);
%marge Phi blue
draw [>=stealth,blue,->] (axis cs:80,-180) -- (axis cs:80,-137);
node at (axis cs:55,-158) {small color{blue} texttt{$M_Phi$}};
%marge Phi Red
draw [>=stealth,red,->] (axis cs:20,-180) -- (axis cs:20,-110);
node at (axis cs:12,-150) {small color{red} texttt{$M_Phi$}};
%marge Phi green
draw [>=stealth,green,->] (axis cs:260,-180) -- (axis cs:260,-157);
node at (axis cs:150,-170) {small color{green} texttt{$M_Phi$}};
end{axis}
end{tikzpicture}
end{minipage}
caption{Diagramme de Bode du correcteur proportionnel}
end{figure}
end{document}