\documentclass[tikz,border=8pt]{standalone}
\usepackage[american]{circuitikz}
\standaloneenv{circuitikz}
\begin{document}
\begin{circuitikz}[voltage shift=0.5]
  \draw
    (0,0) node[ground]{} to[V,invert,l=$V_s$] (0,3)
    to[R,l=$R_s$,i>^=$I_s$] (3.3,3) coordinate(out)
    -- (6.2,3)
    to[R,l=$R_L$,i>^=$I_L$] (6.2,0) node[ground]{};
  \draw (3.3,0) node[ground]{} to[zD,l=$D_Z$,i<_=$I_Z$] (out);
  \draw[->,thick,teal!70!black] (4.15,2.65)--(4.15,0.35)
    node[midway,right] {$V_o\simeq V_Z$};
  \node[above] at (out) {output node};
\end{circuitikz}
\end{document}
