I. Introduction
Phased array systems are widely used in RADAR and satellite communication, with phase shifters being an indispensable component thereof. Phase shifters should be compact, have minimal loss, low-loss variation for different phase shifting states, and a wide bandwidth [1]. The figure of merit (FoM) with which phase shifters are evaluated is defined as [2] \begin{equation*} \mathrm {FoM}=\frac {\Delta \varphi _{\mathrm {max}}}{{\mathrm {IL}}_{\mathrm {max}}}\tag{1}\end{equation*} where is the maximum relative phase shift and is the maximum insertion loss across all phase shifting states.