A high-performance single-pole single-throw (SPST) RF switch for mobile phone RF front-end modules (FEMs) was designed and characterized in a 0.13 μm partially depleted silicon-on-insulator (PD SOI) process. In this paper, the traditional series-shunt configuration design was improved by introducing a suitably large DC bias resistor and leakage-preventing PMOS, together with the floating body technique. The performance of the RF switch is greatly improved. Furthermore, a new R_on × C_off testing method is also proposed. The size of this SPST RF switch is 0.2 mm². This switch can be widely used for present 4G and forthcoming 5G mobile phone FEMs.