RF Characterization of Microwave Power Fet´s

The large-signal S-parameter S₂₂ and the optimum load for maximum output power are two parameters commonly used in the RF characterization of microwave power FET´s. Using a nonlinear circuit model of the device, the dependence on RF power of each of these parameters is investigated. A method is given for computing the optimum load from the Iarge-signal S₂₂. Equivalent load-pull data can thus be obtained without the need for load-pull measurements. The gain compression characteristics of the transistor for arbitrary load can be computed from large-signal S₂₁, and S₂₂ data.