PHEMT MMIC switch for 30 GHz communications systems

A monolithic GaAs Ka-band rf control switch has been developed for use in wireless communications systems. The switch consists of two parallel-resonated GaAs PHEMTs in a shunt single-pole double-throw (SPDT) configuration and has very low dc power dissipation, 1.0 dB insertion loss, and 35 dB isolation. A simple small-signal model is presented to explain the basic features of a resonated PHEMT switch. The switch has a robust design and is adaptable to numerous rf control applications such as phase shifters, transmit inhibit circuits, and broadband wireless LAN systems (WLAN).