Resonated GaAs FET devices for microwave switching

Several designs of monolithic switches for X-band applications have been fabricated and tested. These switches, which consist of two parallel-resonated GaAs FET's in a series SPDT configuration, have very low dc power dissipation, low insertion loss, and are bidirectional. An insertion loss of 0.7 dB with 28-dB isolation at 10.2 GHz has been measured for these devices. A simple equivalent circuit model is presented which explains reasonably well the basic features of resonated GaAs FET switches. The tradeoffs between performance and bandwidth, and the important design criteria, particularly with respect to the layout of monolithic inductors, are investigated.