Optimum power combining configuration for high power amplifiers with broadband performance

This contribution deals with different effects limiting the performance of broadband, high power amplifiers. The question whether a single power device with large parasitics or the power combining of several smaller transistors should be used is studied. Regarding the design of a 100 W, 1.0-2.5 GHz power amplifier using the Cree CGH40xxx GaN-HEMT series, the analysis predicts minimum power degradation if two CGH40045 amplifier units are combined. According to these results, one of the power amplifier units was designed and manufactured. In the 1.0-2.5 GHz band an output power of 60-74 W with a drain efficiency of 47-64 % were measured. From the combining of two amplifier units using surface mount power combiners an output power of more than 104 W can be expected.