## 4 Conclusions  
We demonstrate a 6.5 mW 12.4-32 GHz CMOS down-conversion mixer with a decent CG of 14.4 \(\pm\) 1.5 dB and NF of 7-9.7 dB for 28 GHz 5G NR. A \(\lambda\)/4-TL-C-based coupler is used for harmonic suppression and near-perfect coupling from the RF gm stage to the LO switch transistors. The BSFB technique is used for \(\mathrm{V_{th}}\) and \(\mathrm{V_{DD}}\) reduction. The CCPT-RL-based core IF load is used for \(\mathrm{Z_{L}}\) (i.e., CG) and \(\mathrm{f_{3 dB,IF}}\) boosting. CG and NF enhancement at the same (or even a lower) \(\mathrm{P_{DC}}\) is achieved due to a lower \(\mathrm{V_{DD}}\) and higher gm and \(\mathrm{Z_{L}}\). As a result, low \(\mathrm{P_{DC}}\) and optimized CG, NF, and linearity are achieved for the mixer due to the separate bias (i.e., optimized design) of the gm stage and the IF loads. Conceptualization, Y.-S.L. and K.-S.L. ; methodology, Y.-S.L. and K.-S.L. ; software, K.-S.L. ; validation, Y.-S.L. and K.-S.L. ; formal analysis, Y.-S.L. ; investigation, Y.-S.L. ; resources, \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline  & **CMOS** & **Topology** & **RF Freq** & **LO\({}_{\text{m}}\)** & **CG** & **f\({}_{\text{gg}}\) BW** & **LO-RF** & **NF** & **IFJ** & **P\({}_{\text{DC}}\)** & **Area** & **FOM\({}_{\text{1}}\)** & **FOM\({}_{\text{m}}\)** \\  & **Process** & & **(GHz)** & **(dB)** & **(dB)** & **(GHz)** & **Iso. (dB)** & **(dB)** & **(dB)** & **(dB)** & **(mW)** & **(mm\({}^{3}\))** & **FOM\({}_{\text{1}}\)** & **FOM\({}_{\text{1}}\)** \\ \hline This Work & 90 mm & \
\begin{tabular}{c} Gilbert-cell with \\ \(\lambda\)/4-TL-C-based coupler \\ \end{tabular} & 28 & 0 & 15.6 &
\begin{tabular}{c} 19.6 \\ (12-4-32) \\ \end{tabular} & 46.1 & 7.6 & –1 & 6.5 & 0.494 & 0.023 & 0.14 \\ \hline
[1] & 90 mm & Double-balanced Gilbert-cell & 28 & 1 & –3.3 &
\begin{tabular}{c} 6 \\ (25-31) \\ \end{tabular} & 47.4 & 14.3 & –3.4 & 6.4 & 0.522 & \(8.7\times 10^{-5}\) & \(4.9\times 10^{-3}\) \\ \hline
[2] & 65 mm & Double-balanced Gilbert-cell & 28 & 5 & 7.2 &
\begin{tabular}{c} 13 \\ (26-39) \\ \end{tabular} & N/A & 12.3 & –2.5 & 10.3 & 0.4 & \(6.1\times 10^{-4}\) & 0.017 \\ \hline
[3] & 0.13 \(\mu\)m & \
\begin{tabular}{c} Folded Gilbert-cell \\ \(\mathrm{i}\)-F buffer \\ \end{tabular} & 24 & –3 & 26.1 &
\begin{tabular}{c} 2 \\ (25-25) \\ \end{tabular} & 58 & 7.7 & –27.4 & 16.8 & 0.96 & \(8.9\times 10^{-6}\) & 0.024 \\ \hline
[4] & 0.18 \(\mu\)m & \
\begin{tabular}{c} Gilbert-cell using \\ distributed DS tech. \\ \end{tabular} & 24 & 5 & –4.5 &
\begin{tabular}{c} 4 \\ (22-26) \\ \end{tabular} & N/A & N/A & 23 & 16 & 0.72 & N/A & \(2.48\times 10^{-3}\) \\ \hline
[5] & 90 mm & \
\begin{tabular}{c} Single balance with \\ CCPT feedback \\ \end{tabular} & 60 & 1 & 6.95 &
\begin{tabular}{c} 10 \\ (57-67) \\ \end{tabular} & 50 & 14.4 & 0.2 & 16 & 0.35 & \(42\times 10^{-4}\) & 0.011 \\ \hline
[6] & 40 mm & \
\begin{tabular}{c} Sub-harmonic+ \\ Current-reused \\ \end{tabular} & 60 & 5 & –7.9 &
\begin{tabular}{c} 10.5 \\ (56-57) \\ \end{tabular} & 45 & 14.4 & 0.1 & 3.45 & 0.586 & N/A & \(5.3\times 10^{-3}\) \\ \hline
[7] & 65 mm & \
\begin{tabular}{c} Transformer-coupling \\ cascade topology \\ \end{tabular} & 60/77 & –3 & 9.5 &
\begin{tabular}{c} 28 \\ (28-90) \\ \end{tabular} & 48 & 9.2 & 5.8 & 15 & 0.527 & 0.017 & 0.033 \\ \hline \end{tabular}
\end{table} 
Table 1: Summary of the down-conversion mixer and recently reported state-of-the-art mm-wave down-conversion mixers. Y.-S.L. ; data curation, K.-S.L. ; writing--original draft preparation, K.-S.L. ; writing--review and editing, Y.-S.L. ; visualization, Y.-S.L. ; supervision, Y.-S.L. ; project administration, Y.-S.L. ; funding acquisition, Y.-S.L. All authors have read and agreed to the published version of the manuscript. This research was funded by the National Science and Technology Council (NSTC), Taiwan, grant number MOST111-2221-E-260-017. Not applicable. This work was supported by the National Science and Technology Council (NSTC) of Taiwan under Contract MOST111-2221-E-260-017.