# A Reflection-Type Dual-Band Phase Shifter with an Independently Tunable Phase
## 4 Conclusions  
This paper presents an independently controllable dual-band tunable reflection-type PS. The proposed dual-band PS uses compensation elements to deal with the unwanted parasitic elements of a co-operating band with a shunt open stub and achieves wide PSRs at two operating bands. In the event that the ratio of two operating frequencies is greater than two and less than three, the inductor could be used as the same compensation element for both operating bands. The proposed dual-band PS was verified by fabricating the circuit at 1.88 GHz and 2.44 GHz. Furthermore, the proposed dual-band PS is easy to manufacture and would be useable in a number of diverse dual-band RF circuits and systems. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**References**} & \multirow{2}{*}{\begin{tabular}{c} **Freq.** \\ **[GHz]** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **BW** \\ **[GHz]** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Number** \\ **of** \\ **Variators** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **IL [dB]** \\ **Varators** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **RL [dB]** \\ **VSR [\({}^{\circ}\)]** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **PSR [\({}^{\circ}\)]** \\ **PD [\({}^{\circ}\)]** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Dual-Band** \\ **[mm \(\times\) mm]** \\ \end{tabular} } \\ \hline
[13] & 2 & 0.2 & 6 & \textless{}1.56 & \textgreater{}13.4 & 385 & NA & X & \(81\times 117\) \\ \hline
[14] & 2 & 0.2 & 2 & \textless{}4.6 & \textgreater{}12 & 234 & NA & X & \(49\times 51\) \\ \hline
[15] & 2 & 0.2 & 4 & \textless{}4.6 & \textgreater{}14 & 407 & NA & X & \(69\times 51\) \\ \hline
[16] & 1.5 & 1 & 4 & \textless{}5.8 & \textgreater{}14 & 350 & \(\pm 100\) & X & \(52\times 32\) \\ \hline
[17] & 10 & 2 & 4 & \textless{}3.4 & \textgreater{}10 & 392 & NA & X & NA \\ \hline
[18] & 2.2 & 0.8 & 2 & \textless{}3.2 & \textgreater{}10 & 360 & \(\pm 15\) & X & \(19.4\times 17\) \\ \hline
[19] & 2.5 & 0.5 & 4 & \textless{}1.28 & \textgreater{}15.76 & 146.9 & \(\pm 5.79\) & X & NA \\ \hline
[20] & 10 & 2 & 2 & \textless{}2.3 & \textgreater{}10 & 190 & \(\pm 10\) & X & NA \\ \hline
[24] & 3.5 & 0.02 & \multirow{2}{*}{NA} & \textless{}3.7 & \textgreater{}10 & 360 & \(\pm 3\) & \multirow{2}{*}{Yes} & \(2.3\times 1.2\) \\  & 5.8 & 0.02 & & \textless{}4.5 & \textgreater{}10 & 360 & \(\pm 3\) & & \(\begin{array}{c}\text{(IBM 180-nM}\\ \text{RF CMOS)}\end{array}\) \\ \hline
[25] & 5.9 & 0.2 & \multirow{2}{*}{12} & \textless{}2.8 & \textgreater{}10 & 106 & NA/\(\pm 7\) & \multirow{2}{*}{Yes} & \(0.92\times 1.06\) \\  & 16 & 0.4 & & \textless{}3.5 & \textgreater{}10 & 108 & \(\pm 2/\text{NA}\) & \(\begin{array}{c}\text{(independently)}\\ \end{array}\) & & \(\begin{array}{c}\text{(0.25 um}\\ \text{GaAs process)}\end{array}\) \\ \hline
**This** & **1.88** & **0.1** & \multirow{2}{*}{**4**} & \multirow{2}{*}{**4**} & \multirow{2}{*}{\begin{tabular}{c} **\textless{}1.867** \\ **+1.897** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **\textless{}19.695** \\ **+1.897** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **114.1** \\ **+1.843** \\ **+16.833** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **\textless{}1.843** \\ **114.0** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Yes** \\ **(independently)** \\ \end{tabular} } & \multirow{2}{*}{**85 \(\times\) 52**} \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Performance of the proposed design against state-of-art alternatives. Figure 11: Simulated and measured results of a dual-band PS achieved by simultaneously varying the bias voltages of the low\(-\) and high\(-\)band: (**a**) PSR; (**b**) ILs and input/output RLs. **Author Contributions:** Conceptualization, J.J. and Y.J. ; methodology, S.K. and G.C. ; software, S.K. ; validation, G.C. and Y.J. ; formal analysis, S.K. and G.C. ; investigation, S.K. ; resources, Y.J. ; data curation, S.K. ; writing--original draft preparation, S.K.