# Update (29 Dec 2012)

The author has already update CircuiTikZ (Thank you, Massimo!). It should be integrated into the CTAN official repositories in a few days. The package is now hosted in Github for easier collaboration at https://github.com/mredaelli/circuitikz

I'm having difficulty contacting the author of circuitikz. The email address listed in the README no longer exists; delivery fails permanently.

I needed a fully differential operational amplifier fd op amp, so I created a shape for it.

Kindly have a look at my code at https://github.com/kitmonisit/circuitikz

Some caveats:

1. Basically I added it to pgfcirctripoles.sty. It's supposed to be a quadpole, but I could not figure out how to add it to pgfcircquadpoles.sty and simply changing the declaration line to \pgfdeclarequadpole
2. I may not have followed the convention in specifying the coordinates to enable dynamic scaling. I'll just call out the following new parts so you can check them easily: new anchors out-, out+, and the new output terminals which have been commented with % Positive output terminal and % Negative output terminal

I'm hoping that this new shape will be integrated into the next official version of CircuiTikZ.

## Example usage

\documentclass[preview]{standalone}

\usepackage[siunitx]{circuitikz}

\ctikzset{bipoles/capacitor/height/.initial=.4854}
\ctikzset{bipoles/capacitor/width/.initial=.1}

\begin{document}%
\begin{tikzpicture}
\draw
(0,0) node[fd op amp] (opamp) {} node[left] {$$A$$}
% Input
(opamp.-) node[circ] {} to[C, l_=$$C_s$$] ++(-1.5,0) node[ocirc] {} node[left] {$$v_i^-$$}
(opamp.+) node[circ] {} to[C, l=$$C_s$$] ++(-1.5,0) node[ocirc] {} node[left] {$$v_i^+$$}
% Feedback
(opamp.-) -- ++(0,1)  to[C, l=$$C_f$$] ++(2,0) -| (opamp.out+) {}
(opamp.+) -- ++(0,-1) to[C, l_=$$C_f$$] ++(2,0) -| (opamp.out-) {}
% Output
(opamp.out+) node[circ] {} -- ++(1,0) node[ocirc] {} node[right] {$$v_o^+$$}
(opamp.out-) node[circ] {} -- ++(1,0) node[ocirc] {} node[right] {$$v_o^-$$}
;
\end{tikzpicture}
\end{document}


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## closed as too localized by egreg, lockstep, Charles Stewart, Thorsten, Stefan Kottwitz♦Nov 15 '12 at 10:08

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To get the new email address, follow the instructions in the footnote on page 2 of the manual (ver. Sept. 2011). I wrote him more than a month ago too, but he didn't reply at all. I suspect the development is quiescent. –  Luigi Nov 15 '12 at 8:21