\documentclass[a4paper, 10pt]{article}

% language
\usepackage[italian]{babel}

% figures
\usepackage{graphicx}

% math packages
\usepackage{amsmath}
\usepackage{cancel}

% circuits
\usepackage{pst-circ}

\title{Essenza di Elettronica}
\author{Naoki Pross}

\begin{document}
\maketitle
\include{tex/opamp}
\end{document}