I think this is yet another duplicate of the \shorthandoff{>} problem. Read more here
Labels in TikZ are incorrectly interpreted
Since you don't give a MWE it's not possible to judge hence I'm just guessing it's a spanish setting which produces the same error. You can fix it as the following:
\documentclass{article}
\usepackage[spanish]{babel}
\usepackage{circuitikz}
\begin{document}
\begin{circuitikz}[american]\shorthandoff{>}
\draw (0,0) node[ground]{}
(1.2,4.5) node[op amp] {}
(0,2) to[R, l^=$R_4$, v_>=$V_1^+$, -*] (0,0)
(0,2)--(0,4)
(2.5,2) to[R, l^=$R_3$, i=$i_1$] (0,2)
(2.5,2) to[short, *-](2.5,3.5)
(2.5,3.5) to[R, l^=$R_2$, -*] (4.7,3.5)
(4.7,3.5) to[R, l^=$R_1$] (6.7,3.5)
(6.7,4.5) to[short, -*, i=$i _o$] (6.7,3.5)
(2.2,4.5) to[short, -o] (7.5,4.5)
(3.5,2) node[op amp,xscale=-1] {}
(4.7,1.5) node[ground]{}
(4.7,2.5) --(4.7,3.5)
(0,5) node[ocirc] {}
{[ anchor=east] (0,5) node {$V_i$}}
{[ anchor=west] (7.5,4.5) node {$V_o$}}
{[ anchor=north] (2.5,2) node {$V_o^\prime$}};
\end{circuitikz}
\end{document}
But I can't see any difference in the output so probably it's the default setting.
Is that about right? Are you sure it wouldn't be easier just to stick a node with text where you want it?
\documentclass[a4paper,oneside,titlepage]{article}
\usepackage[utf8]{inputenc}
\usepackage[siunitx]{circuitikz}
\usepackage{tikz}
\usepackage{siunitx}
\begin{document}
\begin{circuitikz}[scale=1.4]\draw
(0,0) to[C, l=\SI{10}{\micro\farad}] (0,2) -- (0,3)
to[R, l=\SI{2.2}{\kilo\ohm}] (4,3) -- (4,2)
to[L, l=\SI{12}{\milli\henry}, i=$i_1$] (4,0) -- (0,0)
(4,2) to[D*, *-*] (2,0) to [D*, -*] (0,2)
to[R, l=\SI{1}{\kilo\ohm}] (2,2) to[cV, v=\SI{0.3}{\kilo\ohm} $i_1$] (4,2)
(2,0) to[I, i=\raisebox{1.2cm}{\SI{1}{\milli\ampere}\hspace{-0.3cm}}, -*] (2,2)
;
\end{circuitikz}
\end{document}
Also, the ne anchor point should be in the vicinity.
\documentclass[a4paper,oneside,titlepage]{article}
\usepackage[utf8]{inputenc}
\usepackage[siunitx]{circuitikz}
\usepackage{tikz}
\usepackage{siunitx}
\begin{document}
\begin{circuitikz}[scale=1.4]\draw
(0,0) to[C, l=\SI{10}{\micro\farad}] (0,2) -- (0,3)
to[R, l=\SI{2.2}{\kilo\ohm}] (4,3) -- (4,2)
to[L, l=\SI{12}{\milli\henry}, i=$i_1$] (4,0) -- (0,0)
(4,2) to[D*, *-*] (2,0) to [D*, -*] (0,2)
to[R, l=\SI{1}{\kilo\ohm}] (2,2) to[cV, v=\SI{0.3}{\kilo\ohm} $i_1$] (4,2)
(2,0) to[I, n=si1, -*] (2,2)
(si1.ne) node[above]{\SI{1}{\milli\ampere}}
;
\end{circuitikz}
\end{document}
Best Answer
You should use the notation
l={<label>}:The result:
The reason behind which the label needs to be grouped in this case can be found in Use math equation as bchart label.