High-efficiency GaAs mesfet amplifiers.

Results obtained in class-AB and class-B operation of GaAs Schottky-barrier field-effect transistors (M.E.S.F.E.T.s) are reported. Under class-B conditions power added efficiencies as high as 61% at 4 GHz and 41% at 8 GHz were obtained. Power added efficiencies of 49%, 40%, and 35% were demonstrated at third order intermodulation levels of -20, -25, and -30 dB, respectively, for 4 GHz 2-carrier operation under class-B conditions. Test data show that GaAs M.E.S.F.E.T. amplifiers are well suited for multicarrier systems requiring high efficiency with low intermodulation distortion, and are potentially applicable as T.W.T.A. drivers and medium-power T.W.T.A. replacements in communications satellites.