Containing a table within page

Question

Because the table is wider than the page, a black stripe appears at the far right. I've tried to put \\ between words on the first line, but that doesn't appear to be the right answer since it breaks everything.

My question is what can I do for the first line (between \toprule and \midrule) to become narrower without changing the font size?

\documentclass{article}
\usepackage{amssymb}
\usepackage{booktabs,threeparttable}

\begin{document}
\begin{table}[ht]
    \caption{Synthesizable circuits summary.}
    \label{tab:summary}
    \centering
    \begin{threeparttable}
        \begin{tabular}{lccccc}
            \toprule
            $\;$ & TDC~[4] & LDO~[8] & VCO~[10] & Flash~ADC~[9] & VCO-based~ADC~[18] \\
            \midrule
            \textbf{Technology~(nm)} & 65 & 130 & 65 & 90 & 65 \\
            \textbf{Synthesizable} & Yes & Yes & Yes & Yes & Yes\textsuperscript{\textdaggerdbl} \\
            \textbf{Supply Voltage~(V)} & 1.2* & 0.6 & 1.2 & 1.2\textsuperscript{$\blacklozenge$} & 1.2* \\
            \textbf{Power~(mW)} & 0.010-0.150\textsuperscript{\textbullet} & --- & --- & 34.8\textsuperscript{$\blacklozenge$} & 1.4 \\
            \textbf{Dye Area~(mm\textsuperscript{2})} & 0.001 & --- & --- & 0.18 & --- \\
            \bottomrule
        \end{tabular}
        \begin{tablenotes}
            \small
            \item * Assumed
            \item \textbullet~Normalized to 1MS/s
            \item $\blacklozenge$~One of the tested modes
            \item \textdaggerdbl~Needs 2 exterior passive components
        \end{tablenotes}
    \end{threeparttable}
\end{table}
\end{document}

The resulting table:

Answer 1

Introducing line breaks in the header cells, not bold-facing the units, and eliminating unneeded whitespace at the left- and right-hand edges of the table makes the tabular material fit inside the text block.

Since you're using the threeparttable package, do make a habit of using its machinery -- \tnote in particular -- correctly.

(The question marks in the following question arise because the \cite instructions couldn't be resolved.)

\documentclass[draft]{article}
\usepackage{threeparttable}
\usepackage{booktabs,amssymb,siunitx} % these three packages are also needed...
\newcommand\gls[1]{#1} % ?? % please provide the correct definition...    
\begin{document}
\begin{table}[ht]
    \caption{Synthesizable circuits summary.}
    \label{tab:summary}
    \centering
    \begin{threeparttable}
        \begin{tabular}{@{} lccccc@{}}
            \toprule
             & \gls{TDC} & \gls{B} & \gls{VCO} & Flash & \gls{VCO}-based  \\
             & \cite{A} & \cite{C} & \cite{D} & \gls{ADC}~\cite{E} & \gls{ADC}~\cite{F} \\
            \midrule
            \textbf{Technology} (\si{\nano\meter}) & 65 & 130 & 65 & 90 & 65 \\
            \textbf{Synthesizable} & Yes & Yes & Yes & Yes & Yes\tnote{\textdaggerdbl} \\
            \textbf{Supply Voltage} (\si{\volt}) & 1.2\tnote{*} & 0.6 & 1.2 & 1.2\tnote{$\blacklozenge$} & 1.2\tnote{*} \\
            \textbf{Power}~(\si{\milli\watt}) & 0.010--0.150\tnote{\textbullet} & -- & -- & 34.8\tnote{$\blacklozenge$} & 1.4 \\
            \textbf{Dye Area}~(\si{\milli\meter\squared}) & 0.001 & -- & -- & 0.18 & -- \\
            \bottomrule
        \end{tabular}
        \begin{tablenotes}
            \small
            \item[*] Assumed
            \item[\textbullet] Normalized to 1MS/s % huh?!
            \item[$\blacklozenge$] One of the tested modes
            \item[\textdaggerdbl] Needs 2 exterior passive components
        \end{tablenotes}
    \end{threeparttable}
\end{table}
\end{document} 

Answer 2

Similar to Mico answer, but for column header I suggest to use thead from makecell package, and for the first column use option >{\bfseries}:

Edit: In the first attempt table still spill out on the right side. Table width equal to text width can be obtained with \begin{tabular*}{\linewidth}{...} and than set column separation by @{\extracolsep{\fill}}:

\documentclass{article}
\usepackage{booktabs, makecell, threeparttable}
\renewcommand\theadfont{\bfseries\normalsize}
\usepackage{amssymb}

\usepackage{showframe}% for shoe page layout, in real application had to be deleted
\renewcommand*\ShowFrameColor{\color{red}}

\begin{document}
\begin{table}[ht]
    \caption{Synthesizable circuits summary.}
    \label{tab:summary}
        \setlength\tabcolsep{3pt}
\centering
\begin{threeparttable}
    \begin{tabular*}{\linewidth}{@{\extracolsep{\fill}}>{\bfseries}lccccc}
        \toprule
    & \thead{TDC\\ \cite{4}} & \thead{LDO\\ \cite{8}} & \thead{VCO\\ \cite{10}} 
            & \thead{Flash ADC\\ \cite{9}} & \thead{VCO-based\\ ADC \cite{18}} \\
        \midrule
Technology (nm)     & 65  & 130    & 65  & 90  & 65 \\
Synthesizable       & Yes & Yes    & Yes & Yes & Yes\tnote{\textdaggerdbl} \\
Supply Voltage (V)  & 1.2\tnote{*} & 0.6 & 1.2 & 1.2\tnote{$\blacklozenge$} & 1.2* \\
Power~(mW)          & 0.010-0.150\tnote{$\bullet$} 
                                   & --- & --- & 34.8\tnote{$\blacklozenge$}& 1.4 \\
Dye Area (mm\textsuperscript{2})
                    & 0.001        & --- & --- & 0.18 & --- \\
        \bottomrule
    \end{tabular*}
    \begin{tablenotes}
        \small
        \item[*]                Assumed
        \item[$\bullet$]        Normalized to 1MS/s
        \item[$\blacklozenge$]  One of the tested modes
        \item[\textdaggerdbl]   Needs 2 exterior passive components
    \end{tablenotes}
\end{threeparttable}
\end{table}
\end{document}