\documentclass[tikz, border=5pt]{standalone}
\usepackage[siunitx]{circuitikz} % Use circuitikz package
\usetikzlibrary{arrows, decorations.markings} % Keep for main plot


\begin{document}

\def\cx{1.75}
\def\cy{-0.25}

\begin{tikzpicture}[
  every node/.style={font=\scriptsize} % Make all annotations smaller
]
  \draw[->] (0, 0) -- (3.2, 0) node[right] {$Z'$};
  \draw[->] (0, 0) -- (0, 1.2) node[above] {$-Z''$};

  % Thick line above x axis with an arrow and text in the middle
  \draw [thick,
         decoration={markings, mark=at position 0.5 with {
           \arrow{>}
           \node[above=2pt] {$R_p || \textrm{CPE}$};
           \node[below=0.5pt] {$\omega\!\uparrow$};
         }},
         postaction={decorate},
         domain=15.25:164.75] plot
         ({\cx+cos(\x)}, {\cy+sin(\x)});

  % Dotted arc below x axis
  \draw [thin,dashed, domain=-15.25:15.25] plot
  ({\cx+cos(\x)}, {\cy+sin(\x)});

  %% Dotted diameter below x axis
  \draw[thin,dashed] ({\cx+cos(164.75)}, {\cy+sin(164.75)}) -- ({\cx+cos(-15.25)}, {\cy+sin(-15.25)});

  % Show the influence of Rs
  \draw[thin, dashed,->]  (0,0.07) -- ({\cx+cos(164.75)}, 0.07) node[midway, above] {$R_s$};

  % --- Equivalent Electrical Circuit (using circuitikz) ---
  \begin{scope}[xshift=3.65cm, yshift=0.5cm, transform shape]
    \ctikzset{bipoles/length=0.3cm} % Adjust component size
    \draw (0,0) to[R, o-, l_=$R_s$] (0.6,0) coordinate(junc); % Rs with start terminal
    \draw (junc) -- ++(0.05,0) coordinate (junc2); % Junction wire
    \draw (junc2) -- ++(0, 0.3) to[R, l=$R_p$] ++(0.8, 0) coordinate (rp_end); % Top branch
    \draw (junc2) -- ++(0,-0.3) to[C, l_=CPE] ++(0.8, 0) coordinate (cpe_end); % Bottom branch
    \draw (rp_end) -- (rp_end |- cpe_end); % Closing vertical wire
    \draw (rp_end |- junc2) to[short, -o] ++(0.2,0); % Add terminal endpoint wire
  \end{scope}

  
\end{tikzpicture}
\end{document}