Question: Is there a way to write the refernce of a figure directly under the Figure?
![enter image description here](https://i.stack.imgur.com/oCicE.png)

```
\documentclass{article}
\usepackage[ngerman]{babel}
\usepackage{filecontents}
\usepackage[backend=biber, citestyle=authoryear]{biblatex}
\addbibresource{my.bib}
\usepackage{caption}
\usepackage[demo]{graphics}
\usepackage{booktabs}   

\begin{filecontents}{my.bib}
    @article{somebody-sgt,
      ids       =   {someone-sgt},
      author    =   {Somebody, Someone},
      title     =   {Some Great Title},
      journal   =   {Best Journal},
      year      =   3019,
      pages     =   {32--39},
      volume    =   3,
      number    =   4}
\end{filecontents}

\begin{document}

\begin{figure}[t!]
\centering
\includegraphics{whatever}
\caption[Test Test,]   {%
  \tabular[t]{@{}l@{}}Test Test, 1. Zeile\\%
  Test Test 2. Zeile \\%
  \hspace{-2.2cm} Quelle:~\cite[S. 23]{somebody-sgt} \endtabular \label{fig:MIMOKanal}}
\end{figure}

\end{document}

```

Answer: 
This should now work (still using tabularx):

```
\documentclass[10pt]{article}
\usepackage{textcomp}
%\usepackage[utf8]{inputenc}
\usepackage{fontspec}
\usepackage[british]{babel}
\usepackage{float}
\usepackage{gensymb}
\usepackage{tabularx,ragged2e,booktabs,caption}
\usepackage{subfigure}
\usepackage{multicol,tabularx,capt-of}
\usepackage{multirow}

\begin{document}

\begin{center}
\renewcommand{\arraystretch}{1.2}
\begin{tabularx}{1\textwidth}{|p{5cm}|X|X|X|X|}
\hline
\multirow{2}{*}{} & \textbf{Conditions} & \multicolumn{2}{c|}{\textbf{Total}} & \multirow{2}{*}{} \\ \cline{2-4}
{} & \textbf{Frequency} & \multicolumn{2}{c|}{\textbf{VDDA+VDD}} & {} \\ \cline{1-5}
\textbf{Mode} & \textbf{CLK} & \textbf{Type} & \textbf{Max} & \textbf{Unit} \\ \hline
Power Down (TBC) & 0 Hz & 0.6 & 2.00 & $\mu$A \\ \hline
\end{tabularx}
\captionof{table}{Current Consumption}
\end{center}

\end{document}

```
You don't need to load `multirow` with this slighly modified layout. Instead, the `makecell` package defines a `\thead` command for cells with a common formatting (say, `\bfseries` here) and you can use `\\` inside theses cells. I also used `booktabs` and suppressed vertical lines for more "professional looking" table.

You don't need it here, but please note that `subfigure` and `subfig` are deprecated now (the former no more maintained) and you should use `subfloat` or `floatrow`.

You should put put your tabulars in a table, not `center`, environment and so use `\caption`. Anyway, if you really had to use `\captionof`, it is defined in the `caption` package. Also don't load several times the same package.

```
\documentclass[10pt]{article}
\usepackage{fontspec}
\usepackage[british]{babel}
\usepackage{float}
\usepackage{booktabs,caption}
\usepackage{multicol,tabularx}
\usepackage{array}
\usepackage{makecell}
\renewcommand\theadfont{\bfseries}
\usepackage{siunitx}

\begin{document}

\begin{table}[!htbp]
\renewcommand{\arraystretch}{1.2}
\begin{tabular}{@{\,}l*{4}{c}@{\,}}
\cmidrule[\heavyrulewidth]{2-4}
& \thead{Conditions \\Frequency}
  & \multicolumn{2}{c}{\thead{Total \\ VDDA + VDD}}\\
\toprule
\textbf{Mode} & \thead{CLK} & \thead{Type} & \thead{Max} & \thead{Unit} \\
\midrule
Power Down (TBC) & 0 Hz & 0.6 & 2.00 & \si{\micro\ampere} \\
\bottomrule
\end{tabular}
\caption{Current Consumption}
\end{table}

\end{document} 

```

![enter image description here](https://i.stack.imgur.com/7f1oJ.png)