Tables: aligning text and equation

Question

I'm trying to allign a normal cell with text together with another one in which I have an equation. For instance, I want OB2B and SSMF to be aligned with their corresponding equations.

Here is my code:

\documentclass{article}
\usepackage{amsmath}
\usepackage{array}
\begin{document}
    
\begin{table}[h!]
    \caption{Current amplitude response at low frequencies in the mmW band (small signal regime)}
    \centering
    \small
    \renewcommand{\arraystretch}{2} % adjust row spacing
    \begin{tabular}{p{1.5cm}p{8cm}}
    \hline\hline
    & \centering\arraybackslash $i(2\omega_{RF}\pm\omega_{IF})$ \\
    \hline
    
    OB2B & 
    \begin{minipage}[t]{8cm}\vspace{0pt}
    \begin{equation}
    \Re P_0 m_{AM}m_{RF}^2 \sin^2 \varphi_{DC} 
    \label{gain_OB2B}
    \end{equation}
    \end{minipage} \\
    
    SSMF & 
    \begin{minipage}[t]{8cm}\vspace{0pt}
    \begin{equation}
    \Re P_0 m_{AM}m_{RF}^2 \sin^2 \varphi_{DC}
    \left(1 \pm j \alpha \kappa P_0 \beta L \omega_{RF}\right)
    \label{gain_SSMF}
    \end{equation}
    \end{minipage} \\
    
    \hline\hline
    \end{tabular}
    \label{gainTable1}
    \end{table}

\end{document}

Answer 1

Like this:

• Instead of tabular I would rather use tblr of tabularray package and for equation term use X column type. By this I'm able to remove minipages.
• For numbering and labeling of equation I would use separate columns (see MWE below)
• I took a liberty and introduce some new packages (as tabularray libraries), which enable to write nicer table. Similar for caption I would use options of caption package (you can redesign it according to your taste or requirement):

\documentclass{article}
\usepackage{tabularray}
\UseTblrLibrary{amsmath,
                booktabs,
                counter,
                siunitx}
\usepackage[skip=1ex,
            font=small,
            labelfont=bf,
            hang]{caption}

\begin{document}
\begin{equation}
a^2 + b^2 = c^2
\end{equation}
    \begin{table}[!ht]
\caption{Current amplitude response at low frequencies in the \unit{\milli\meter\watt} % what is mmW?
         band (small signal regime)}
\label{gainTable1}
\small
\begin{tblr}{colspec = {Q[l, m, wd=1.5cm] 
                        X[c, m, mode=dmath] 
                        Q[r] @{}},
             cell{2-Z}{Z} = {cmd=\refstepcounter{equation}}
            }
    \toprule
        &   i(2\omega_{\mathrm{RF}}\pm\omega_{\mathrm{IF}})            
            &                  \\
    \midrule    
OB2B    &   \Re P_0 m_{AM}m_{RF}^2 \sin^2 \varphi_{DC}
            &   (\theequation)\label{gain_OB2B} \\
SSMF    &   \Re P_0 m_{AM}m_{RF}^2 \sin^2 \varphi_{DC}
            \bigl(1 \pm j \alpha \kappa P_0 \beta L \omega_{RF}\bigr)
            &   (\theequation)\label{gain_SSMF} \\
    \bottomrule
\end{tblr}
    \end{table}
\begin{equation}
c^2 - b^2 = a^2
\end{equation}    
See equations \eqref{gain_OB2B} and \eqref{gain_SSMF} \dots
\end{document}

Edit:
I extend first version MWE so, that show that equation numbering is correct and that referencing works as expected.

Addendum:
Some off-topic suggestions:

• I would indices which are not variables write with with upright letters.
• For a bit better positioning of indices I would use subdepth package.
• For shorter write I also would declare a new math operators (using amsmath package):

\documentclass{article}
\usepackage{tabularray}
\UseTblrLibrary{amsmath,
                booktabs,
                counter,
                siunitx}
\DeclareMathOperator{\AM}{AM}   % new
\DeclareMathOperator{\RF}{RF}   % new
\DeclareMathOperator{\DC}{DC}   % new
\usepackage[low-sup]{subdepth}  % new, for subscript positioning

\usepackage[skip=1ex,
            font=small,
            labelfont=bf,
            hang]{caption}

\begin{document}
\begin{equation}
a^2 + b^2 = c^2
\end{equation}
    \begin{table}[!ht]
\caption{Current amplitude response at low frequencies in the \unit{\milli\meter\watt} % what is mmW?
         band (small signal regime)}
\label{gainTable1}
\small
\begin{tblr}{colspec = {Q[l, m, wd=1.5cm] 
                        X[c, m, mode=dmath] 
                        Q[r] @{}},
             cell{2-Z}{Z} = {cmd=\refstepcounter{equation}}
            }
    \toprule
        &   i(2\omega_{\RF}\pm\omega_{\mathrm{IF}})            
            &                  \\
    \midrule    
OB2B    &   \Re P_0 m_{\AM}m_{\RF}^2 \sin^2 \varphi_{\DC}
            &   (\theequation)\label{gain_OB2B} \\
SSMF    &   \Re P_0 m_{\AM}m_{\RF}^2 \sin^2 \varphi_{\DC}
            \bigl(1 \pm j \alpha \kappa P_0 \beta L \omega_{\RF}\bigr)
            &   (\theequation)\label{gain_SSMF} \\
    \bottomrule
\end{tblr}
    \end{table}
\begin{equation}
c^2 - b^2 = a^2
\end{equation}    
See equations \eqref{gain_OB2B} and \eqref{gain_SSMF} \dots
\end{document}

Answer 2

I'd fake an equation environment.

\documentclass{article}
\usepackage{amsmath}
\usepackage{array,booktabs}
\usepackage{caption} % for captions above tables

\newcounter{lequation}
\newcommand{\lequation}[1]{%
  \refstepcounter{equation}%
  \stepcounter{lequation}\label{leq\thelequation}%
  \hspace*{\fill}$\displaystyle{#1}$\hspace*{\fill}\eqref{leq\thelequation}%
}

\begin{document}
    
\begin{table}[htp!]
\centering
\small

\caption{Current amplitude response at low frequencies in the mmW band (small signal regime)}
\label{gainTable1}

\begin{tabular}{@{} l w{c}{8cm} @{}}
\toprule
    & $i(2\omega_{RF}\pm\omega_{IF})$ \\
\midrule
OB2B & \lequation{
         \Re P_0 m_{\mathrm{AM}}m_{\mathrm{RF}}^2 \sin^2 \varphi_{\mathrm{DC}}
         \label{gain_OB2B}
       } \\
\addlinespace
SSMF & \lequation{
         \Re P_0 m_{\mathrm{AM}}m_{\mathrm{RF}}^2 \sin^2 \varphi_{\mathrm{DC}}
         (1 \pm j \alpha \kappa P_0 \beta L \omega_{\mathrm{RF}})
         \label{gain_SSMF}
       } \\
\bottomrule
\end{tabular}

\end{table}

\eqref{gain_OB2B} and \eqref{gain_SSMF}

\end{document}

An internal label is set in order to be able to use \eqref independently on assigned labels.