\newcommand\height{2.0}
\draw [] (0, \height/2)                       coordinate (vip) 
   to [short,o-,i=$\underline{I}_{\mathrm{I}}$] ++ (1,0) coordinate (x)
    to [short,-]                                ++ (0,-0.5);
 \draw (1, 0) ellipse (0.3 and 0.5);

\draw [] (0,-\height/2) coordinate (vin) to [short,o-] ++ (1,0) 
        to [short,-]                                ++ (0,0.5);


\draw (3, \height/2) coordinate (vop)  
     to [short,o-,i<_=$\underline{I}_{\mathrm{O}}$] ++ (-1,0)
    to [short,-]                                ++ (0,-0.5);

\draw (3, -\height/2)  coordinate (von) 
    to [short,o-*] ++ (-1,0) coordinate (gnd) 
    to [short,-]   ++ (0,0.5);

\draw (2, -0.25) ellipse (0.25 and 0.25); 
\draw (2,  0.25) ellipse (0.25 and 0.25); 
\node[ground] at (gnd) {};

\path [voltarrow] (vip) edge node [midway,left,inner sep=2pt] 
  {$\underline{V}_{\mathrm{I}}$} (vin);
\path [voltarrow] (vop) edge node [midway,right,inner sep=2pt] 
  {$\underline{V}_{\mathrm{O}}$} (von);

\node[anchor=east] at (vip) {INP};
\node[anchor=east] at (vin) {INN};
\node[anchor=west] at (vop) {O};