This paper describes a $0.13-{mu}m$ CMOS RF switch for $3{sim}5$ GHz UWB band(mode 1). It can improve isolation characteristics between ports by using deep n-well RF devices while their source and body terminals are separated. From the measurement results, the proposed T/R switch is comparative to the on-wafer probing measurement results of the series-shunt T/R switches. When the proposed T/R switch operates as Tx mode, measured insertion loss from Tx to output port is less than 1.5 dB and isolation between Tx and Rx is more than 27 dB for $3{sim}5$ GHz. Return loss for the Tx port is more than -10 dB and input P1dB is +10 dBm.