# LPF (Low Pass Filter) block

I am trying to generate a LPF block with TikZ.

I have found out the option of drawing a LPF with CircuiTikZ:

\documentclass[border=10pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes,arrows,positioning}
\usetikzlibrary{arrows.meta}
\usepackage{circuitikz}

\tikzset{
block/.style = {draw, fill=white, rectangle, minimum height=3em, minimum width=3em},
tmp/.style  = {coordinate},
input/.style = {coordinate},
output/.style= {coordinate},
pinstyle/.style = {pin edge={to-,thin,black}
}
}

\begin{document}

\begin{tikzpicture}
\node [input, name=input] {};
\node [block, right=20mm of input] (A) {A};
\node [block, right=20mm of A] (B) {B};
\draw [-{Latex[length=2mm]}] (A) to[lowpass](B);
\end{tikzpicture}

\end{document}


This has 2 problems:

1. The line connecting blocks goes through them, and does not start at their edge.
2. There is no arrow pointing towards the LPF

I have unsuccessfully tried to find a workaround to this.

Is there any way I could make it look like this?

(As a last request, is it also possible to make the border of the block have the same thickness as A and B?)

• Welcome to TeX.SX! Please don't post code fragments. Instead, put your fragments into a complete compilable document that shows the problem. Aug 26, 2017 at 11:48
• @Thruston Code updated Aug 26, 2017 at 12:06
• Forget it, I didn't read that you were using circuitikz. Aug 26, 2017 at 12:26

\documentclass[tikz, margin=3mm]{standalone}
\usetikzlibrary{arrows.meta, positioning}
\usepackage{circuitikz}

\begin{document}
\begin{tikzpicture}[box/.style={draw, thick, minimum size=10mm}]
\node [box] (A) {A};
\node [box, right=20mm of A] (B) {B};
\path (A) to [lowpass, name=lpf] (B);
\draw [-{Latex[length=2mm]}] (A.east) to (lpf.west);
\draw [-{Latex[length=2mm]}] (lpf.east) to (B.west);
\end{tikzpicture}
\end{document}


edit: if you like change lowpass border thickness, than you only need redefine bipoles thickness:

\ctikzset{bipoles/thickness=1}


and above image you can redraw in:

complete mwe is:

\documentclass[margin=3mm]{standalone}
\usepackage{circuitikz}
\usetikzlibrary{arrows.meta, positioning}

\begin{document}
\begin{tikzpicture}[
box/.style = {draw, inner sep=2pt, minimum size=10mm},
LA/.style = {-{Latex[length=2mm]}},
node distance = 22mm
]
\ctikzset{bipoles/thickness=1}
%
\node [box] (A) {A};
\node [box, right=of A] (B) {B};
\path (A) to [lowpass, name=lpf] (B);
\draw [LA] (A) to (lpf.west);
\draw [LA] (lpf.east) to (B);
\end{tikzpicture}
\end{document}

• It works perfectly. Is it possible however to make the LPF block's border less thick instead of increasing A's and B's thickness? Aug 26, 2017 at 12:53
• @tuuli, see edit of my answer. Aug 26, 2017 at 13:59