Passive MESFET Limiters For Wireless Applications

The ability to sharply limit power level while maintaining a negligible change in phase is important in many wireless communications systems. This paper investigates the use of a passive MESFET device as a power limiter for the UHF and lower microwave frequency range. The S-parameters of a commercial grade GaAs FET were measured as a function of power level and used to develop a model. From the model a limiter circuit was designed, fabricated and tested. The resulting limiter employed two FETs in cascade, and produced a near ideal transfer characteristic over more than a two decade power range with less than a 15 degree change in phase.