我想绘制一个 Bode 图并使用 tikz 交点显示相位裕度。
以下是我所做的：
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[european]{circuitikz}
\usepackage{tikz}
\usetikzlibrary{shapes, calc, intersections}
\usepackage{pgfplots}
\pgfplotsset{compat=1.14}
\usetikzlibrary{pgfplots.groupplots}
\usepackage{siunitx}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsfonts}
\usepackage{subcaption}
\renewcommand*{\j}{\mathrm{j}}
\begin{document}
\begin{figure}[h]
\begin{tikzpicture}[trim axis right, remember picture]
\begin{semilogxaxis}[
name=mag,
width=\linewidth,
height=0.5\linewidth,
ylabel=$20\log_{10}\left(|H\!(\j2\pi f)\right|)$,
%xlabel=$f\,/\,\si{\Hz}$,
xmin=1000, xmax=1e10,
grid=both, minor grid style=dotted, minor y tick num = 4,
xticklabels={}]
\addplot [thick, name path=mag] table[x=Magnitude X, y=Magnitude Y, col sep=comma] {bode.csv};
\draw[red, thick, name path=0dB] (axis cs:1e3,0) -- (axis cs:1e10,0);
\end{semilogxaxis}
\begin{semilogxaxis}[
name=phase,
at={($(mag.south) - (0,0.05\linewidth)$)},
anchor=north,
width=\linewidth,
height=0.5\linewidth,
xmin=1000, xmax=1e10,
xlabel=$f\,/\,\si{\Hz}$,
ylabel=$\arg\{H(\j2\pi\omega)\}$,
grid=both, minor grid style=dotted, minor y tick num = 4]
\addplot [thick, name path= phase] table[x=Phase X, y=Phase Y, col sep=comma] {bode.csv};
\draw[red, thick, name path= PM] (axis cs:1e3,0) -- (axis cs: 1e10,0) coordinate (pmend);
\end{semilogxaxis}
\path [draw, name intersections={of=mag and 0dB,by={intmag}}, name path=vertical] (intmag) coordinate (IM) -- (IM|-phase.south);
\draw [latex-latex, name intersections={of=vertical and PM, by={intpm}}] (intpm) -- (intpm|-pmend) node[midway, left] {$PM$};
\end{tikzpicture}
\caption{Closed-loop Bode plot without Miller compensation}
\end{figure}
\end{document}
这是我的结果。
这是错误的。它应该看起来与这张图片中的粉红色线条相似。
我认为我的代码的问题与在轴环境内外使用的坐标系有关，这导致结果错误。
我该如何修复它？
谢谢
PD：csv 文件这里
答案1
感谢您的更新。也许最简单的方法是提取上图交点的 x 值，并在下图中使用它来获取第二个交点。另请参阅这个答案为什么你的交叉路口被移动了。
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{tikz}
\usepackage{pgfplots}
\pgfplotsset{compat=1.14}
\usepgfplotslibrary{groupplots,fillbetween}
\usepackage{siunitx}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsfonts}
\usepackage{subcaption}
\renewcommand*{\j}{\mathrm{j}}
\begin{document}
\begin{figure}[h]
\begin{tikzpicture}[trim axis right, remember picture]
\begin{groupplot}[group style={group size=1 by 2,
horizontal sep=0pt,vertical sep=12pt},%disabledatascaling,
height=0.5\linewidth,width=\linewidth,xmode=log, ymode=normal]
\nextgroupplot[
% name=mag,
ylabel=$20\log_{10}\left(|H\!(\j2\pi f)\right|)$,
%xlabel=$f\,/\,\si{\Hz}$,
xmin=1000, xmax=1e10,
grid=both, minor grid style=dotted, minor y tick num = 4,
xticklabels={}]
\addplot [thick, name path=mag] table[x=Magnitude X, y=Magnitude Y, col sep=comma] {bode.csv};
\draw[red, thick, name path=0dB] (axis cs:1e3,0) -- (axis cs:1e10,0);
\path [name intersections={of=mag and 0dB,by={intmag}}]
(intmag) \pgfextra{\pgfplotspointgetcoordinates{\pgfpointanchor{intmag}{center}}
\xdef\myx{\pgfkeysvalueof{/data point/x}}\typeout{\myx}};
\nextgroupplot[
name=phase,
xmin=1000, xmax=1e10,
xlabel=$f\,/\,\si{\Hz}$,
ylabel=$\arg\{H(\j2\pi\omega)\}$,
grid=both, minor grid style=dotted, minor y tick num = 4]
\addplot [thick, name path global=phase] table[x=Phase X, y=Phase Y, col sep=comma] {bode.csv};
\draw[red, thick, name path global=PM] (axis cs:1e3,0) -- (axis cs: 1e10,0) coordinate (pmend);
\path[name path=vert] (\myx,0) coordinate(low) -- (\myx,200);
\path [name intersections={of=vert and phase,by={vertPM}}];
\end{groupplot}
%\path [draw,name path=vertical] (intmag) coordinate (IM) -- (IM|-phase.south);
\draw (intmag) -- (low);
\draw [latex-latex] (low) -- (vertPM) node[midway, left] {$PM$};
\end{tikzpicture}
\caption{Closed--loop Bode plot without Miller compensation.}
\end{figure}
\end{document}
