Circuit Example

<tex> \documentclass[border=10pt,12pt]{standalone} \usepackage[siunitx]{circuitikz} % Loading circuitikz with siunitx option \begin{document} \begin{circuitikz}[american currents,european resistors]

 \draw %horizontal main components
   (0,0) node[coordinate](origin){} to[short,*-] ++(1,0)
   to[R,l=$r_{bx}$,name=Rbx]    ++(2,0) node [coordinate] (bx) {$b_x$}
   to[R,l=$r_{bi}/q_b$,name=Rbi] +(2,0) node [coordinate] (bi) {$b_i$}
   to[C,l=$c_{bc}$,name=Cbc]     +(4,0) node [coordinate] (ci) {$c_i$}
   to[R,l=$r_{ci}$,name=Rci]     +(2,0) node [coordinate] (rc)      {}
   to[R,l=$r_{cx}$,-*,name=Rcx]  +(2,0) node [coordinate] (c)       {}
 ;
 \draw %current sources
   ($(bi)+(0.3,0)$) |- ++(1,2) node [coordinate] (t2) {}
   to[cI=$i_{bc}-i_{gc}$,name=c1] (t2-|ci)
   ($(ci)+(-0.3,0)$) to[cI=$i_{ce}$,name=c3] ++(0,-3) node [coordinate] (t3) {}
   ($(bi)+(1,0)$) node[coordinate](t4){} to[cI=$i_{be}$,name=c2] (t4|-t3)
 ;
 \draw %qbe and cbcx
   (bx) |- ++(1,4) node[coordinate](t1) {}
   to[C,l=$c_{bcx}$,name=Cbcx] (t1-|ci)
   (bi) to[C,l_=$q_{be}$,name=qbe] (bi|-t3)
   (t1-|ci)--(ci)
 ;
 \draw
   ($(bi|-t3)!0.5!(t3)$)            node [coordinate] (t5) {}
   to[R,l=$r_{e}$,name=Re] ++(0,-2) node [coordinate] (t6) {}
   (bi|-t3)--(t3)
 ;
 \draw
   ($(rc)!0.5!(rc|-t6)$) node[coordinate] (t7) {}
   (rc) to[C,l=$C_{cs}$,name=Ccs] (t7)
   (t7) to[R,l=$r_{s}$,name=Rs] (rc|-t6)
   (origin|-t6) to[short,*-*] (t6-|c)
 ;
 %labels
 \draw (origin|-t6) node [anchor=south]       {$e$}
       (t6-|c)      node [anchor=south]       {$e$}
       (c)          node [anchor=north]       {$c$}
       (origin)     node [anchor=north]       {$b$}
       (bx)         node [anchor=north]      {$bx$}
       (bi)         node [anchor=south]      {$bi$}
       (ci)         node [anchor=south east] {$ci$}
       (t5)         node [anchor=south]      {$ei$};

 %nonlinear lines (messy)
 \begin{scope}[thick]
   \def\doff{0.1}
   %horizontal Resistors
   \draw ($(Rbi.sw)-(0.2,\doff)$) --  ($(Rbi.sw)+(0,-\doff)$)
     --  ($(Rbi.ne)+(0,\doff)$)   -- ($(Rbi.ne)+(0.2,\doff)$)
         ($(Rci.sw)-(0.2,\doff)$) --  ($(Rci.sw)+(0,-\doff)$)
     --  ($(Rci.ne)+(0,\doff)$)   -- ($(Rci.ne)+(0.2,\doff)$);

   %horizontal Capacitors
   \draw ($(Cbc.nw)+(-0.2,\doff)$)  --     ($(Cbc.nw)+(0,\doff)$)
     --  ($(Cbc.se)-(0,\doff)$)     --  ($(Cbc.se)-(-0.2,\doff)$)
         ($(Cbcx.nw)+(-0.2,\doff)$) --    ($(Cbcx.nw)+(0,\doff)$)
     --  ($(Cbcx.se)-(0,\doff)$)    -- ($(Cbcx.se)-(-0.2,\doff)$)
         ($(c1.nw)+(-0.2,\doff)$)   --      ($(c1.nw)+(0,\doff)$)
     --  ($(c1.se)-(0,\doff)$)      --   ($(c1.se)-(-0.2,\doff)$);

   %vertical curr
   \draw ($(c3.nw)+(0.2,\doff)$) --   ($(c3.nw)+(0,\doff)$)
     --  ($(c3.se)-(0,\doff)$)   -- ($(c3.se)-(0.2,\doff)$)
         ($(c2.nw)+(0.2,\doff)$) --   ($(c2.nw)+(0,\doff)$)
     --  ($(c2.se)-(0,\doff)$)   -- ($(c2.se)-(0.2,\doff)$);

   % Vertical c
   \draw ($(qbe.nw)+(0.2,\doff)$) --   ($(qbe.nw)+(0,\doff)$)
     --  ($(qbe.se)-(0,\doff)$)   -- ($(qbe.se)-(0.2,\doff)$)
         ($(Ccs.nw)+(0.2,\doff)$) --   ($(Ccs.nw)+(0,\doff)$)
     -- ($(Ccs.se)-(0,\doff)$)    -- ($(Ccs.se)-(0.2,\doff)$);
 \end{scope}

\end{circuitikz} \end{document} </tex>