\documentclass{article}
\usepackage[pdftex,active,tightpage]{preview}
\setlength\PreviewBorder{0mm}

\usepackage{circuitikz}
\usepackage{tikz}
\usetikzlibrary{positioning}

\begin{document}
\begin{preview}
  \begin{circuitikz}
    \draw (0,2) node[european nand port] (mynand1){};
    \draw (0,0) node[european nand port] (mynand2){};
    \draw (2.5,1.73) node[european nand port] (mynand3){};
    \draw (2.5,0.28) node[european nand port] (mynand4){};

    \draw (mynand1.in 1) node[ocirc,label=left:$D$]{};
    \draw (mynand2.in 2) node[circ] (lowerConnection) {};
    \draw (-2.3,-0.27) node[ocirc,label=left:$E$] (E) {};
    \draw (E) -- (lowerConnection);
    \draw (mynand1.out) -- (mynand3.in 1);
    \draw (mynand2.out) -- (mynand4.in 2);
  \end{circuitikz}
\end{preview}
\end{document}