\begin{tikzpicture}
	\tikzstyle{node}=[circle,draw=black!50,fill=black,minimum size=2pt,inner sep=0pt]
	\tikzstyle{block}=[draw=black,rectangle,fill=none,minimum size=1cm, inner sep=0pt]
	\begin{axis}[
		axis lines*=middle,
		enlargelimits = false, clip=false,
		ymin=-4, ymax=5,
		xmin=-5, xmax=5,
		axis line style={->,>=stealth},
		xlabel={$x$},
		ylabel={$Q(x)$},
		yticklabel style = {yshift=0.2cm},
		xticklabel style = {yshift=-0.1cm},
		every axis x label/.style={
			at={(ticklabel* cs:1)},
			anchor=west,
		},
		every axis y label/.style={
			at={(ticklabel* cs:1)},
			anchor=south,
		},
		ytick={-4, -3,-2, 1, 2, 3},
		yticklabels={$-4\Delta$, $-3\Delta$, $-2\Delta$, $\Delta$, $2\Delta$, $3\Delta$},
		xtick={-4.5,...,4.5},
		xticklabels={$-\frac{9\Delta}{2}$, $-\frac{7\Delta}{2}$, $-\frac{5\Delta}{2}$, $-\frac{3\Delta}{2}$, $-\frac{\Delta}{2}$, $\frac{\Delta}{2}$, $\frac{3\Delta}{2}$, $\frac{5\Delta}{2}$, $\frac{7\Delta}{2}$, $\frac{9\Delta}{2}$},
		every outer y axis line/.append style={white!15!black},
		every y tick label/.append style={font=\color{white!15!black}},
		legend style={draw=white!15!black,fill=white,legend cell align=left}]			
		\addplot[line width=1pt] coordinates {(0, 0) (1/2, 0) (1/2, 1) (3/2, 1) (3/2, 2) (5/2, 2) (5/2, 3) (5, 3)};
		\addplot[line width=1pt] coordinates {(0, 0) (-1/2, 0) (-1/2, -1) (-3/2, -1) (-3/2, -2) (-5/2, -2) (-5/2, -3) (-7/2, -3) (-7/2, -4) (-5, -4)};
		\addplot[dashed, black!20, line width=1pt, domain=-4:4, samples=2] {x};
		
		\draw[black!10, fill=black!10] (axis cs: -6, 4) rectangle (axis cs: -1, 2) {};
		\node[node] (xc) at (axis cs: -5.5, 3) {};
		\node[block, right=0.75cm of xc, text width = 1cm, align= center] (Q) {$Q$};
		\coordinate[right=0.75cm of Q] (yc) {};
		
		\path[->, >=stealth, shorten >= 0pt, draw=black!50] (xc) edge (Q);
		\path[->, >=stealth, shorten >= 0pt, draw=black!50] (Q) edge (yc);
		
		\node[above = 0mm of xc, text width = 1cm, align=center] {$x[n]$};
		\node[above = 0mm of yc, align=center] {$x_Q[n]$}; 
		
		\draw[<->, >=stealth, blue2, line width=2pt] (axis cs: -4.5, 0.25) -- (axis cs: 3.5, 0.25) {};
		\node at (axis cs: 2.5, 0.75) {\color{blue2} $\Delta X$}; 
	\end{axis}
\end{tikzpicture}